#include <cstring>

int main(){

int n,m,x,y;

scanf("%d%d%d%d",&n,&m,&x,&y);

long long f[26][26];

int i,j;

for(i=0;i<=25;i++)

for(j=0;j<=25;j++)

f[i][j]=1;

if(x>=2&&y>=1) f[x-2][y-1]=0;

if(x>=2) f[x-2][y+1]=0;

if(x>=1&&y>=2) f[x-1][y-2]=0;

if(x>=1) f[x-1][y+2]=0;

if(y>=2) f[x+1][y-2]=0;

f[x+1][y+2]=0;

if(y>=1) f[x+2][y-1]=0;

f[x+2][y+1]=0;

f[x][y]=0;

for(i=0;i<=25;i++){

for(j=0;j<=25;j++){

if(f[i][j]==0) continue;

if(i==0&&j-1>=0){ f[i][j]=f[i][j-1]; continue;}

if(j==0&&i-1>=0){ f[i][j]=f[i-1][j]; continue;}

if(i==0&&j==0){ f[i][j]=1; continue;}

f[i][j]=f[i-1][j]+f[i][j-1];

}

}

printf("%lld",f[n][m]);

return 0;

}