题解

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
using namespace std;
bool f[25][25];
long long dp[25][25],n,m,x,y;
int main(){
	cin>>n>>m>>x>>y;
    n+=2;
    m+=2;
    x+=2;
    y+=2;
    f[x][y]=1;
    f[x-2][y-1]=1;
    f[x-2][y+1]=1;
    f[x-1][y-2]=1;
    f[x-1][y+2]=1;
    f[x+2][y-1]=1;
    f[x+2][y+1]=1;
    f[x+1][y-2]=1;
    f[x+1][y+2]=1;
    dp[2][2]=1;
    for(int i=2;i<=n;i++)
    {
    	for(int j=2;j<=m;j++)
    	{
    		if(i==2 && j==2)
    		{
    			continue;
			}
			if(f[i][j]==1)
			{
				continue;
			}
			dp[i][j]=dp[i-1][j]+dp[i][j-1];
		}
	} 
	cout<<dp[n][m];
}