C++ :

#include <cstdio>
#include <cstring>
int main(){
    int n, m, hx, hy;
    if(scanf("%d %d %d %d", &n, &m, &hx, &hy) != 4) return 0;
    static int bad[64][64];
    memset(bad, 0, sizeof(bad));
    int dx[] = {0, 1, 1, 2, 2, -1, -1, -2, -2};
    int dy[] = {0, 2, -2, 1, -1, 2, -2, 1, -1};
    for(int k=0;k<9;k++){
        int x = hx + dx[k], y = hy + dy[k];
        if(x >= 0 && x <= n && y >= 0 && y <= m) bad[x][y] = 1;
    }
    static long long f[64][64];
    memset(f, 0, sizeof(f));
    for(int i=0;i<=n;i++) for(int j=0;j<=m;j++){
        if(bad[i][j]){ f[i][j] = 0; continue; }
        if(i == 0 && j == 0){ f[i][j] = 1; continue; }
        long long v = 0;
        if(i > 0) v += f[i-1][j];
        if(j > 0) v += f[i][j-1];
        f[i][j] = v;
    }
    printf("%lld\n", f[n][m]);
    return 0;
}