欧拉计划 Problem2

#include<iostream>

using namespace std;

const int maxn = 4000000; 
int main()
{
    long a = 1,b = 2;
    long sum = 2;
    while(a<maxn||b<maxn)
    {
        a = a + b;
        b = a + b;
        if(a%2==0)
            sum += a;
        if(b%2==0)
            sum += b;
    }
    cout << sum;
}