diff --git a/assignments/bmi_calculator/bmi_calculator.js b/assignments/bmi_calculator/bmi_calculator.js
index 0cdd351..9669ad7 100644
--- a/assignments/bmi_calculator/bmi_calculator.js
+++ b/assignments/bmi_calculator/bmi_calculator.js
@@ -1,6 +1,16 @@
 // This function should return the BMI for a person 
 function BMICalculator(mass, height) {
     // Write your code here
+    if (mass<=0){
+        return "INVALID INPUT"
+    }
+    else if (height<=0){
+        return "INVALID INPUT"
+    }
+    else{
+        BMI=mass/(height*height)
+        return BMI
+    }
 }
 
 module.exports = BMICalculator;