Maximum Sized Square formed in 01 Matrix

/* dpw4112001 */

#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define MOD 1000000007
#define f first
#define i insert
#define all(x) x.begin(),x.end()
#define s second
#define pb push_back
#define MX 1000005
#define IO ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define int long long

int32_t main()
{IO;
    int t;
    cin >> t;
    while(t--)
    {
        int n,m;
        cin >> n >> m;
        int mat[n][m];
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                cin >> mat[i][j];
            }
        }
        int mx=0;
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<m;j++)
            {
                mx=max(mx,mat[i][j]);
                if(i==0 || j==0)
                    continue;
                if(mat[i][j]==0)
                continue;
                mat[i][j]+=min(mat[i-1][j],min(mat[i][j-1],mat[i-1][j-1]));
                mx=max(mx,mat[i][j]);
            }
        }
        cout<<mx<<'\n';   
    }
    return 0;
}