#include <stdio.h>
int main() {
    int f1f, f1b, f2f, f2b, g1, g2, hb;
    scanf("%d %d", &f1f, &f1b);
    scanf("%d %d", &f2f, &f2b);
    scanf("%d %d", &g1, &g2);
    f1b -= g1;
    if(f1b < 0) {
        g1 += f1b;
        f2f -= f1b;
        f1f += f1b;
    }
    f2b += g1;
    f2f -= g2;
    if(f2f < 0) g2 += f2f;
    printf("%d\n", f1f += g2);
    return 0;
}