Project Euler Problem 2: Even Fibonacci numbers

Even Fibonacci numbers

Problem 2

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

C++:

#include <iostream>

using namespace std;

const long N = 4000000;

int main()
{
    long f1 = 1, f2 = 2, f3;
    long ans = f2;

    for(;;) {
        f3 = f1 + f2;
        if(f3 > N)
            break;

        if(f3 % 2 == 0) {
            ans += f3;
        }

        f1 = f2;
        f2 = f3;
    }

    cout << ans << endl;

    return 0;
}

Python:

ls=[1,1]
ans=0
while ls[-1] <4000000:
	ls.append(ls[-1]+ls[-2])
	if (ls[-1]&1) == 0:
		ans+=ls[-1]

print(ans)

Run results:
4613732