#include "bits/stdc++.h"
#define Rep(i,n) for(int i=0;i<(int)(n);i++)
#define For(i,n1,n2) for(int i=(int)(n1);i<(int)(n2);i++)
#define REP(i,n) for(ll i=0;i<(ll)(n);i++)
#define RREP(i,n) for(ll i=((ll)(n)-1);i>=0;i--)
#define FOR(i,n1,n2) for(ll i=(ll)(n1);i<(ll)(n2);i++)
#define RFOR(i,n1,n2) for(ll i=((ll)(n1)-1);i>=(ll)(n2);i--)
#define all(a)  (a).begin(),(a).end()
#define IOS std::cin.tie(0),std::ios::sync_with_stdio(false)

namespace idaten {

	using namespace std;
	using ll = int_fast64_t;
	using ull = uint_fast64_t;
	using P = std::pair<int64_t, int64_t>;
	template<typename T1, typename T2> inline bool chmin(T1& a, T2 b) { if (a > b) { a = b; return 1; }return 0; }
	template<typename T1, typename T2> inline bool chmax(T1& a, T2 b) { if (a < b) { a = b; return 1; }return 0; }
	template<class Type>struct is_vector : std::false_type {};
	template<class ValueType, class Alloc>struct is_vector<std::vector<ValueType, Alloc>> : std::true_type {};
	template <typename T> inline std::ostream& operator << (std::ostream& out, const std::vector<T>& v) {
		if (v.empty())return out;
		constexpr bool is_vector_v = is_vector<T>::value;
		if (is_vector_v)for (auto itr = v.begin(); itr != v.end();)out << (*itr), out << ((++itr != v.end()) ? "\n" : "");
		else for (auto itr = v.begin(); itr != v.end();)out << (*itr), out << ((++itr != v.end()) ? " " : "");
		return out;
	}
	inline void put() {}
	template<class T> inline void put(const T& first) { std::cout << first << "\n"; }
	template<class T, class... N> inline void put(const T& first, const N& ... rest) { std::cout << first << " "; put(rest...); }
	inline void putn() {}
	template<class T, class... N> inline void putn(const T& first, const N& ... rest) { std::cout << first << "\n"; putn(rest...); }

	template<typename T>
	vector<vector<T>> WarshalFloyd(vector<vector<T>>& path,T inf) {
		int n = path.size();
		vector<vector<int>> res = path;
		vector<vector<int>> next(n, vector<int>(n, 0));
		for (int i = 0; i < n; ++i) {
			for (int j = 0; j < n; ++j) {
				next[i][j] = j;
			}
		}
		// Warshal Floyd
		for (int k = 0; k < n; ++k) {
			for (int i = 0; i < n; ++i) {
				for (int j = 0; j < n; j++) {
					if (res[i][k] != inf && res[k][j] != inf && (res[i][j] == inf || res[i][j] > res[i][k] + res[k][j])) {
						res[i][j] = res[i][k] + res[k][j];
						next[i][j] = next[i][k];
					}
				}
			}
		}
		bool negative_cycle = false;
		for (int k = 0; k < n; ++k) {
			for (int i = 0; i < n; ++i) {
				for (int j = 0; j < n; j++) {
					if (res[i][k] != inf && res[k][j] != inf && (res[i][j] == inf || res[i][j] > res[i][k] + res[k][j])) {
						negative_cycle = true;
						res[i][j] = -inf;
					}
					if (res[i][k] == -inf || res[k][j] == -inf) {
						res[i][j] = -inf;
					}
				}
			}
		}
		// iからjへの経路を復元
		/*vector<vector<vector<int>>> res(n, vector<vector<int>>(n));
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; ++j) {
				for (int cur = i; cur != j; cur = next[cur][j]) {
					res.push_back(cur);
				}
			}
		}*/
		return res;
	}

	void solve() {
		IOS;
		int n, m;
		cin >> n >> m;
		int inf = INT_MAX / 2;
		vector<vector<int>> path(n, vector<int>(n, inf));
		REP(i, n) {
			path[i][i] = 0;
		}
		REP(i, m) {
			int a, b, c;
			cin >> a >> b >> c;
			//a--, b--;
			chmin(path[a][b], c);
		}
		auto d = WarshalFloyd(path, inf);
		REP(i, n) {
			REP(j, n) {
				if (d[i][j] == -inf) {
					put("NEGATIVE CYCLE");
					return;
				}
			}
		}
		REP(i, n) {
			REP(j, n) {
				if (d[i][j] == inf) {
					cout << "INF";
				} else {
					cout << d[i][j];
				}
				if (j != n - 1) {
					cout << " ";
				}
			}
			cout << "\n";
		}
	}
} // namespace idaten

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



Measured memory_bytes: 3356