大佬求助：

#include<bits/stdc++.h>
#define ll long long
#define de double
using namespace std;
ll n,m,x,y;
ll mv[9][2]={{0,0},{1,-2},{2,1},{2,-1},{1,2},{-1,2},{-2,1},{-2,-1},{-1,-2}};
ll f[100][100];
int main(){
	scanf("%lld%lld%lld%lld",&n,&m,&x,&y);
	for(ll i=0;i<9;i++){
		ll sx=x+mv[i][0];
		ll sy=y+mv[i][1];
		if(sx>=0&&sx<=n&&sy>=0&&sy<=m)
			f[sx][sy]=-1;
	}
	f[0][0]=1;
	for(ll i=0;i<=n;i++)
		for(ll j=0;j<=m;j++){
			if(i==j&&j==0||f[i][j]<0)
				continue;
			ll t1=0,t2=0;
			if(f[i-1][j]>0)
				t1=f[i-1][j];
			if(f[i][j-1]>0)
				t2=f[i][j-1];
			f[i][j]=t1+t2;
		}
	printf("%lld",f[n][m]);
	return 0;
}