#include<bits/stdc++.h>
#define LL long long
#define P pair<int,int>
#define fi first
#define se second
#define fr(x) freopen(#x".in","r",stdin);freopen(#x".out","w",stdout);
using namespace std;
const int N=1e6+5;
int T,n,m,s;P w[N],f[N<<1];bool v[N<<1];
vector<int>a[N];
inline bool chk(int x)
{
	for(int i=0;i<=n+m;i++) v[i]=0; 
	for(int i=0;i<=x;i++)
	{
		auto [u,v]=w[i];
		if(::v[u+v]) return 0;::v[u+v]=1;
		f[u+v]={u,v};
	}
	for(int i=2;i<n+m;i++)
	{
		auto [u,v]=f[i];auto [U,V]=f[i+1];
		if(!::v[i]||!::v[i+1]) continue;
		if(!((u+1==U&&v==V)||(u==U&&v+1==V))) return 0;
	}return 1;
}
int main()
{
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);cin>>T;
	while(T--)
	{
		cin>>n>>m;s=n*m;
		for(int i=1;i<=n;i++)
		{
			a[i].resize(m+3);
			for(int j=1;j<=m;j++) cin>>a[i][j],w[a[i][j]]={i,j};
		}
		int l=0,r=s-1,mid,ans;
		while(l<=r)
		{
			mid=(l+r)>>1;
			if(chk(mid)) ans=mid,l=mid+1;
			else r=mid-1;
		}cout<<ans+1<<"\n";
	}
	return 0;
}