#include<bits/stdc++.h>
using namespace std;

#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,s,n) for(int i=(s);i<=(n);i++)
#define repr(i,n) for(int i=n-1;i>=0;i--)
#define REPR(i,s,n) for(int i=(s);i>=(n);i--)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define Eunique(v) v.erase(unique(all(v)),v.end())
#define Eback(s) s.erase(s.end()-1,s.end())
#define rev(v) reverse(all(v))
#define minvec(v) *min_element(all(v))
#define maxvec(v) *max_element(all(v))
#define sumvec(v) accumulate(all(v),0LL)
#define mapmin(v) v.rbegin()->first
#define mapmax(v) v.begin()->first
#define pb push_back
#define pf push_front
#define m_p make_pair
#define DOUBLE fixed << setprecision(15)
#define OK cerr<<"OK\n"
#define OK1 cerr<<"OK1\n"
#define OK2 cerr<<"OK2\n"
#define SIZE(s) (int)s.size()
#define INF ((1LL<<62)-(1LL<<31))
#define zero(x,n) setw(x) << setfill('0') << n
#define endl '\n'

typedef long long ll;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<long long> vll;
typedef vector<vll> vvll;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<string> vs;

typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<pair<int,int>> vpii;
typedef vector<pair<ll,ll>> vpll;

const double pi = acos(-1.0);
const ll mod=1000000007;
const ll mod2=998244353;

template<class A, class B>
ostream& operator<<(ostream& ost, const pair<A, B>&p) {
	ost << "{" << p.first << ", " << p.second << "} ";
	return ost;
}

template<class T>
ostream& operator<<(ostream& ost, const vector<T>&v) {
	ost << "{";
	for (int i = 0; i<(int)v.size(); i++) {
		if (i)ost << " ";
		ost << v[i];
	}
	ost << "} \n";
	return ost;
}

template<class A, class B>
ostream& operator<<(ostream& ost, const map<A, B>&v) {
	ost << "{";
	for (auto p:v) {
		ost << "{" << p.first << ", " << p.second << "} ";
	}
	ost << "} ";
	return ost;
}

template<class T>
inline bool chmax(T& a, T b){if(a<b){a=b;return true;} return false;}

template<class T>
inline bool chmin(T& a, T b){if(a>b){a=b;return true;} return false;}

void YES(bool b) {cout << ((b)?"YES\n":"NO\n");}
void Yes(bool b) {cout << ((b)?"Yes\n":"No\n");}
void yes(bool b) {cout << ((b)?"yes\n":"no\n");}
void Yay(bool b) {cout << ((b)?"Yay!\n":":(\n");}

ll powmod(ll a,ll b){ll c=1; while(b>0){ if(b&1){ c=a*c%mod; } a=a*a%mod; b>>=1; } return c;}
ll nCrmod(ll n,ll r){ll x=1,y=1; rep(i,r){x=x*(n-i)%mod; y=y*(i+1)%mod;} return x*powmod(y,mod-2)%mod;}
ll gcd(ll x, ll y) {return __gcd(x,y);}
ll lcm(ll x, ll y) {return x/__gcd(x,y)*y;}

template<typename T>
struct edge{
    long long src;
	long long to;
    T cost;
};

template<typename T>
using Edges=vector<edge<T>>;

template<typename T>
vector<T> bellman_ford(Edges<T> &edges,int V,int s){
    vector<T> dist(V,INF);
    dist[s]=0;
    for(int i=0;i<V-1;i++){
        for(auto& e:edges){
            if(dist[e.src]==INF) continue;
            dist[e.to]=min(dist[e.to],dist[e.src]+e.cost);
        }
    }
    for(auto& e:edges){
        if(dist[e.src]==INF) continue;
        if(dist[e.src]+e.cost<dist[e.to]) return vector<T>();
    }
    return dist;
}

int main()
{
	ll n,m;
	cin >> n >> m;
	vvll v(n,vll(n,INF));
	rep(i,n) v[i][i]=0;
	Edges<ll> g;
	g.resize(n);
	rep(i,m){
		ll s,t,d;
		cin >> s >> t >> d;
		g.push_back({s,t,d});
		v[s][t]=d;
	}
	auto dist=bellman_ford(g,n,0);
	if(dist.empty()) cout << "NEGATIVE CYCLE\n";
	else{
		rep(k,n)rep(i,n)rep(j,n){
			if(v[i][k]!=INF && v[k][j]!=INF){
				chmin(v[i][j],v[i][k]+v[k][j]);
			}
		}
		rep(i,n){
			rep(j,n){
				if(v[i][j]==INF) cout << "INF";
				else cout << v[i][j];
				cout << (j==n-1?"\n":" ");
			}
		}
	}
	return 0;
}


Measured memory_bytes: 3364