求助，这个为什么不能运行？QAQ

#include<iostream>
#include<cmath>
using namespace std;
long long m,n,x,y,ans,a[100][100];
void cool(int i,int j)
{if(i==m&&j==n) {ans++;return;}
 if(i+1>=0&&i+1<=m&&a[i+1][j]!=1) cool(i+1,j);
 if(y+1>=0&&y+1<=n&&a[i][j+1]!=1) cool(i,j+1);
return;
}
int main()
{cin>>m>>n>>x>>y;
 m+=2;n+=2;x+=2;y+=2;
 a[x][y]=1;a[x+1][y+2]=1;a[x+2][y+1]=1;a[x+2][y-1]=1;
 a[x+1][y-2]=1;a[x-1][y-2]=1;a[x-2][y-1]=1;a[x-2][y+1]=1;a[x-1][y+2]=1;
 cool(2,2);
 cout<<ans;
 return 0; 
}