Question: this program supposes to do this quotfibonacci sequence starts with...

This program supposes to do this

"Fibonacci sequence starts with 0 and 1 where each fibonacci number is a sum of two previous fibonacci numbers. Given an integer N, find the sum of all even fibonacci numbers."

Example) input = 12

output = 10 because 2 + 8 = 10

In this program, n is for nth fibonacci number and sum is for sum of all even numbers that question asked for.

However, I always got the 0 for the sum value ( nth number prints out correct all the time).

I don't know why this happens.

Can someone explain it to me why this method can't calculate the sum and also what am I suppose to fix it??

This is C++ fyi.

Thank you :)