#include<stdio.h>
#include<stdlib.h>
int bx,by,cx,cy;
long long m[30][30];
int main(){
    scanf("%d %d %d %d",&bx,&by,&cx,&cy);
    for(int i = 0;i<=bx;i++){
        for(int j = 0;j<=by;j++){
            m[i][j] = m[i-1][j] + m[i][j-1];
            if(i==0 && j==0) m[i][j] = 1;
            if(abs(i-cx)*abs(i-cx)+abs(j-cy)*abs(j-cy)==5) m[i][j] = 0;
            if(i==cx && j==cy) m[i][j] = 0;
        }
    }
    printf("%lld",m[bx][by]);
    return 0;
}