#include <bits/stdc++.h>
using namespace std;
int b1,b2,m1,m2;
long long f[40][40];
bool g[40][40];
int main(){
	cin >> b1 >> b2 >> m1 >> m2;
	g[m1][m2]=1;
	if(m1-1>=0&&m1-2>=0) g[m1-1][m2-2]=1;
	if(m1+1<=b1&&m2-2>=0) g[m1+1][m2-2]=1;
	if(m1-2>=0&&m2-1>=0) g[m1-2][m2-1]=1;
	if(m1+2<=b1&&m2-1>=0) g[m1+2][m2-1]=1;
	if(m1-1>=0&&m2+2<=b2) g[m1-1][m2+2]=1;
    if(m1-2>=0&&m2+1<=b2) g[m1-2][m2+1]=1;
	if(m1+1<=b1&&m2+2<=b2) g[m1-1][m2+2]=1;
	if(m1+2<=b1&&m2+1<=b2) g[m1-2][m2+1]=1;
	for(int i=0;i<=b1;i++){
		for(int j=0;j<=b2;j++){
			if(!g[i][j]){
				if(i==0&j==0) f[0][0]=1;
				else if(i>0&&j==0)f[i][0]=f[i-1][0];
				else if(i==0&&j>0) f[0][j]=f[0][j-1];
				else f[i][j]=f[i-1][j]+f[i][j-1];
			}
		}
	}
	printf("%11d\n",f[b1][b2]);
	return 0;
}

感觉也没啥问题啊，可是样例都没过啊啊啊

stO 大佬 Ort