一直编译错误。。。

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,m,dp[2502][2502],a[2502][2502],s[2502][2502];
int main(){
	ios::sync_with_stdio(false);
	while(cin>>n>>m){
		memset(dp,0,sizeof(dp));int ans=0;
		memset(s,0,sizeof(s));
		for(int i=1;i<=n;i++){
			for(int j=1;j<=m;j++){
				cin>>a[i][j];
				s[i][j]=s[i-1][j]+s[i][j-1]-s[i-1][j-1]+a[i][j];
				if(a[i][j]==0) dp[i][j]=0;
				else dp[i][j]=dp[i-1][j-1]+1;
				int k=dp[i][j];
				while(s[i][j]-s[i-k][j]-s[i][j-k]+s[i-k][j-k]!=k && k>0) k--;
				dp[i][j]=k;
				ans=max(ans,k);
			}
		}memset(dp,0,sizeof(dp));
		memset(s,0,sizeof(s));
		for(int i=1;i<=n;i++){
			for(int j=m;j>=1;j--){
				s[i][j]=s[i-1][j]+s[i][j+1]-s[i-1][j+1]+a[i][j];
				if(a[i][j]==0) dp[i][j]=0;
				else dp[i][j]=dp[i-1][j+1]+1;
				int k=dp[i][j];
				while(s[i][j]-s[i-k][j]-s[i][j+k]+s[i-k][j+k]!=k && k>0) k--;
				dp[i][j]=k;
				ans=max(ans,k);
			}
		}
		cout<<ans<<endl;
	}
}