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.
*/
#include <iostream>
#include <vector>
using namespace std;

int main (){
 int i, j, k,sum = 0, even = 2;
 const int upper_bound = 4000000;
 std::vector<int> only={1, 2};
 while(sum < upper_bound){
   i = only[only.size() - 1];
   j = only[only.size() - 2];
   sum = i + j;
   only.push_back(sum);
   if(sum % 2 == 0){
      even=even+sum;
  }
 }
cout<< even <<endl;
cout<< sum <<endl;
return 0;
}