#include <bits/stdc++.h>
using namespace std;

signed main(){
  int Aw, Ab; cin >> Aw >> Ab;
  int Bw, Bb; cin >> Bw >> Bb;
  int C, D; cin >> C >> D;
  Bw += max( 0, C - Ab );
  Aw -= max( 0, C - Ab );
  Aw += min( D, Bw );
  cout << Aw << endl;
  return 0;
}