为什么输出和答案一样却是wa

#include<iostream>
using namespace std;
int n,m,x,y,f[403][403],s[403][403];
int head=1,tail=2,b[401][403];
int main()
{
	cin>>n>>m>>x>>y;
	f[head][1]=x;
	f[head][2]=y;
	b[x][y]=1;
	while(head<tail)
	{
		int i=f[head][1];
		int j=f[head][2];
		if(i+1<=n&&j+2<=m&&b[i+1][j+2]==0)
		{
			b[i+1][j+2]=1;
			f[tail][1]=i+1;
			f[tail][2]=j+2;
			s[i+1][j+2]=s[i][j]+1;
			tail++;	
		}
		if(i+2<=n&&j+1<=m&&b[i+2][j+1]==0)
		{
			b[i+2][j+1]=1;
			f[tail][1]=i+2;
			f[tail][2]=j+1;
			s[i+2][j+1]=s[i][j]+1;
			tail++;	
		}
		if(i>=3&&j+1<=m&&b[i-2][j+1]==0)
		{
			b[i-2][j+1]=1;
			f[tail][1]=i-2;
			f[tail][2]=j+1;
			s[i-2][j+1]=s[i][j]+1;
			tail++;
		}
		if(i+1<=n&&j-2>=1&&b[i+1][j-2]==0)
		{
			b[i+1][j-2]=1;
			f[tail][1]=i+1;
			f[tail][2]=j-2;
			s[i+1][j-2]=s[i][j]+1;
			tail++;
		}
		if(i>=3&&j>=2&&b[i-2][j-1]==0)
		{
			b[i-2][j-1]=1;
			f[tail][1]=i-2;
			f[tail][2]=j-1;
			s[i-2][j-1]=s[i][j]+1;
			tail++;	
		}
		if(i>=2&&j>=3&&b[i-1][j-2]==0)
		{
			b[i-1][j-2]=1;
			f[tail][1]=i-1;
			f[tail][2]=j-2;
			s[i-1][j-2]=s[i][j]+1;
			tail++;
		}
		if(i>=2&&j+2<=m&&b[i-1][j+2]==0)
		{
			b[i-1][j+2]=1;
			f[tail][1]=i-1;
			f[tail][2]=j+2;
			s[i-1][j+2]=s[i][j]+1;
			tail++;
		}
		if(i+2<=n&&j>=2&&b[i+2][j-1]==0)
		{
			b[i+2][j-1]=1;
			f[tail][1]=i+2;
			f[tail][2]=j-1;
			s[i+2][j-1]=s[i][j]+1;
			tail++;
		}
		head++;
	}
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=m;j++)
		{
			if(s[i][j]!=0)
					cout<<s[i][j]<<" ";
			else
				if(i==x&&j==y)
					cout<<0<<" ";
				else
					cout<<"-1"<<" ";
		}
		cout<<endl;
	}	
	return 0;
}