diff --git a/src/main.rs b/src/main.rs
index 08fbf2f..7bd7a72 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,13 +3,20 @@ use std::process;
 
 fn main() {
     let args: Vec<String> = env::args().collect();
+    if args.len() != 2 {
+        println!("Error: You need to run this program with exactly 1 argument");
+        process::exit(1);
+    }
     let equation = computorv1::parse(&args[1]).unwrap_or_else(|e| {
         println!("Error during parsing: {e}");
         process::exit(1);
     });
     println!("{:?}", equation);
     let is_equation = computorv1::maths::evaluator::is_equation(&equation);
-    let evaluated = computorv1::maths::evaluator::evaluate(equation);
+    let evaluated = computorv1::maths::evaluator::evaluate(equation).unwrap_or_else(|e| {
+        println!("Error during evaluation: {e}");
+        process::exit(1);
+    });
     computorv1::pretty(&evaluated);
     if is_equation {
         computorv1::maths::solver::solve(evaluated);
diff --git a/src/maths/evaluator.rs b/src/maths/evaluator.rs
index 6c863df..2db1a4b 100644
--- a/src/maths/evaluator.rs
+++ b/src/maths/evaluator.rs
@@ -69,15 +69,15 @@ fn mul(lhs: Vec<GaussianRational>, rhs: &Vec<GaussianRational>) -> Vec<GaussianR
     res
 }
 
-fn exp(lhs: Vec<GaussianRational>, rhs: Vec<GaussianRational>) -> Vec<GaussianRational> {
+fn exp(lhs: Vec<GaussianRational>, rhs: Vec<GaussianRational>) -> Result<Vec<GaussianRational>, String> {
     if rhs.len() != 1 {
-        panic!("Eh t'y es fou mon gate puissance d'inconnu !");
+        return Err(format!("exponential only supports natural exponents, unknown exponents aren't supported"));
     }
     if rhs[0].imaginary.numerator != 0 {
-        panic!("Diablerie une puissance complexe !");
+        return Err(format!("exponential only supports natural exponents, complex exponents aren't supported"));
     }
     if rhs[0].real.denominator != 1 {
-        panic!("MON DIEU UNE PUISSANCE DE RATIONNEL");
+        return Err(format!("exponential only supports natural exponents, rational exponents aren't supported"));
     }
     let mut res = Vec::new();
     let pow = rhs[0].real.numerator;
@@ -85,7 +85,7 @@ fn exp(lhs: Vec<GaussianRational>, rhs: Vec<GaussianRational>) -> Vec<GaussianRa
     for _ in 0..pow {
         res = mul(res, &lhs);
     }
-    res
+    Ok(res)
 }
 
 fn check_div(lhs: &Vec<GaussianRational>, rhs: &Vec<GaussianRational>) -> bool {
@@ -97,12 +97,12 @@ fn check_div(lhs: &Vec<GaussianRational>, rhs: &Vec<GaussianRational>) -> bool {
     true
 }
 
-fn div(lhs: Vec<GaussianRational>, rhs: Vec<GaussianRational>) -> Vec<GaussianRational> {
+fn div(lhs: Vec<GaussianRational>, rhs: Vec<GaussianRational>) -> Result<Vec<GaussianRational>, String> {
     if rhs.len() > lhs.len() {
-        panic!("faut pas diviser par plus grande puissance d'inconnu que sois meme :$");
+        return Err(format!("division supported if the divisor to be of same or smaller degree than the dividend."));
     }
     if !check_div(&lhs, &rhs) {
-        panic!("Moi je sais pas faire heing");
+        return Err(format!("division supported if the divisor has only one non zero coefficient"));
     }
 
     let denominator = *rhs.last().unwrap();
@@ -117,17 +117,18 @@ fn div(lhs: Vec<GaussianRational>, rhs: Vec<GaussianRational>) -> Vec<GaussianRa
         res[res_i] = lhs[i] / denominator;
     }
 
-    res
+    Ok(res)
 }
 
-fn calculate(operator: Token, lhs: Vec<GaussianRational>, rhs: Vec<GaussianRational>) -> Vec<GaussianRational> {
+fn calculate(operator: Token, lhs: Vec<GaussianRational>, rhs: Vec<GaussianRational>) -> Result<Vec<GaussianRational>, String> {
     match operator {
-        Token::Addition() => add(lhs, rhs),
-        Token::Substraction() => sub(lhs, rhs),
-        Token::Multiplication() => mul(lhs, &rhs),
+        Token::Addition() => Ok(add(lhs, rhs)),
+        Token::Substraction() => Ok(sub(lhs, rhs)),
+        Token::Multiplication() => Ok(mul(lhs, &rhs)),
         Token::Division() => div(lhs, rhs),
         Token::Exponentiation() => exp(lhs, rhs),
-        Token::Equal() => sub(lhs, rhs),
+        Token::Equal() => Ok(sub(lhs, rhs)),
+        Token::Modulo() => Err(format!("modulo isn't suported yet by this program.")),
         _ => unreachable!(),
     }
 }
@@ -140,11 +141,11 @@ fn calculate_unary(operator: Token, operand: Vec<GaussianRational>) -> Vec<Gauss
     }
 }
 
-pub fn evaluate(ast: Node) -> Vec<GaussianRational> {
+pub fn evaluate(ast: Node) -> Result<Vec<GaussianRational>, String> {
     match ast {
-        Node::Binary { operator, lhs, rhs } => calculate(operator, evaluate(*lhs), evaluate(*rhs)),
-        Node::Unary { operator, operand } => calculate_unary(operator, evaluate(*operand)),
-        Node::Leaf(value) => value,
+        Node::Binary { operator, lhs, rhs } => calculate(operator, evaluate(*lhs)?, evaluate(*rhs)?),
+        Node::Unary { operator, operand } => Ok(calculate_unary(operator, evaluate(*operand)?)),
+        Node::Leaf(value) => Ok(value),
     }
 }
 
diff --git a/src/maths/solver.rs b/src/maths/solver.rs
index cef3e36..289cdcc 100644
--- a/src/maths/solver.rs
+++ b/src/maths/solver.rs
@@ -35,6 +35,8 @@ pub fn solve(mut equation: Vec<GaussianRational>) -> Vec<GaussianRational> {
     for i in (1..equation.len()).rev() {
         if equation[i] == zero() {
             equation.pop();
+        } else {
+            break;
         }
     }
     crate::pretty(&equation);