#include <iostream>
#include <climits>
using namespace std;
#define	int long long
const int INF=1e18;
const int MAX_V=2000;
int v,g[MAX_V][MAX_V],r;
void warshall(){
  for(int k=0;k<v;k++)
    for(int i=0;i<v;i++)
      for(int j=0;j<v;j++) g[i][j]=min(g[i][j],g[i][k]+g[k][j]);
}
signed main(){
  int e;
  cin>>v>>e;
  for(int i=0;i<v;i++) for(int j=0;j<v;j++) g[i][j]=i==j?0:INF;
  for(int i=0,a,b,c;i<e&&cin>>a>>b>>c;i++) g[a][b]=c;
  warshall();
  //for(int i=0;i<v;i++) for(int j=0;j<v;j++) if(INF/2<g[i][j]&&g[i][j]<INF) r++;                                              
  for(int i=0;i<v;i++) if(g[i][i]) r++;
  if(r){
    cout<<"NEGATIVE CYCLE"<<endl;
    return 0;
  }
  for(int i=0;i<v;i++){
    for(int j=0;j<v;j++){
      if(j) cout<<" ";
      if(g[i][j]>=INF/2) cout<<"INF";
      else cout<<g[i][j];
    }
    cout<<endl;
  }
  return 0;
}
#include <iostream>
#include <algorithm>

using namespace std;
static const int SIZE = 101;
static const long long int INF = 1e18;
long long int d[SIZE][SIZE] = { 0 };

void solve()
{
	for (int i = 0; i < SIZE; ++i)
	{
		for (int j = 0; j < SIZE; ++j)
		{
			d[i][j] = INF;
		}
		d[i][i] = 0;
	}
	int V, E;
	cin >> V >> E;
	for (int i = 0; i < E; ++i)
	{
		int from, to, cost;
		cin >> from >> to >> cost;
		d[from][to] = cost;
	}
	for (int k = 0; k < V; ++k)
	{
		for (int i = 0; i < V; ++i)
		{
			for (int j = 0; j < V; ++j)
			{
				if (d[i][k] != INF && d[k][j] != INF)
				{
					d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
				}
			}
		}
	}
	bool isNegative = false;
	for (int i = 0; i < V; ++i)
	{
		if (d[i][i] < 0)
		{
			cout << "NEGATIVE CYCLE" << endl;
			return;
		}
	}
	for (int i = 0; i < V; ++i)
	{
		for (int j = 0; j < V; ++j)
		{
			if (j)
			{
				cout << " ";
			}
			if (d[i][j] == INF)
			{
				cout << "INF";
			}
			else
			{
				cout << d[i][j];
			}
		}
		cout << endl;
	}
}

int main()
{
	solve();
	return(0);
}