这哪有问题？？？

#include<bits/stdc++.h>
using namespace std;
long long dp[30][30];
bool b[30][30];
int main(){
	int n,m,x,y;
	cin>>n>>m;
	cin>>x>>y;
	b[x][y]=1;
	b[x-2][y-1]=1;
	b[x-2][y+1]=1;
	b[x-1][y-2]=1;
	b[x-1][y+2]=1;
	b[x+1][y-2]=1;
	b[x+1][y+2]=1;
	b[x+2][y-1]=1;
	b[x+2][y+1]=1;
	dp[0][1]=1;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			if(b[i][j])continue;
			dp[i][j]=dp[i][j-1]+dp[i-1][j];
		}
	}
	cout<<dp[n][m];
	return 0;
}