#include <iostream>

int main(void){
    // Your code here!
    int aw, ab, bw, bb;
    int c, d;
    std::cin >> aw >> ab;
    std::cin >> bw >> bb;
    std::cin >> c >> d;
    
    int move;
    move = (ab >= c)? c:ab;
    bb += move;
    ab -= move;

    move = (move == c)? 0:c - move;
    bw += move;
    aw -= move;
    
    move = (bw >= d)? d:bw;
    aw += move;
    
    std::cout << aw << std::endl;
    
    return 0;
}