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;
    }
}