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

const int64_t MOD = 1e9 + 7;

int main() {
  int64_t Aw, Ab, Bw, Bb, C, D;
  cin >> Aw >> Ab >> Bw >> Bb >> C >> D;
  if (C <= Ab && D >= Bw) cout << (Aw + Bw) << endl;
  else if (C <= Ab && D < Bw) cout << (Aw + D) << endl;
  else if (C > Ab && D >= (Bw + C - Ab)) cout << (Aw + Bw) << endl;
  else if (C > Ab && D < (Bw + C - Ab)) cout << (Aw - C + Ab + D) << endl;
  else cout << "0" << endl;
  return 0;
}