#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
int main() {
  int a1,a2,b1,b2,c,d;
  cin >> a1 >> a2 >> b1 >> b2 >> c >> d;
  if(a2>=c) {
      a1-=0;
  }
  else {
      a1-=(c-a2);
      b1+=c-a2;
  }
  a1+=min(d,b1);
  cout << a1 << endl;
}