#include <stdio.h>

#define MAXN 25

long long dp[MAXN][MAXN]={0},ma[MAXN][MAXN]={0};
long long xb, yb, xm, ym;

int main() {
    scanf("%lld %lld %lld %lld", &xb, &yb, &xm, &ym);
    xb++;yb++;xm++;ym++;
    ma[xm][ym]=1;
    ma[xm-1][ym-2]=1;
    ma[xm-2][ym-1]=1;
    ma[xm-2][ym+1]=1;
    ma[xm-1][ym+2]=1;
    ma[xm+1][ym-2]=1;
    ma[xm+2][ym-1]=1;
    ma[xm+2][ym+1]=1;
    ma[xm+1][ym+2]=1;
    dp[1][1]=1;
    for (int i = 1; i <= xb; i++) {
        for (int j = 1; j <= yb; j++) {
        	if (i==1&&j==1) continue;
            if (ma[i][j]==0) {
                dp[i][j]=dp[i-1][j]+dp[i][j-1];
            }
        }
    }
    printf("%lld\n",dp[xb][yb]);
    return 0;
}

上面的代码是我按照题解的思路写的代码，代码除了变量名几乎与题解没有差别，为什么会出现RE呀！