#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <string>
#include <math.h>
#include <iomanip>
#include <limits>
#include <list>
#include <queue>
#include <tuple>
#include <map>
#include <stack>
#include <set>
#include <bitset>
using namespace std;
#define fast_io ios_base::sync_with_stdio (false) ; cin.tie(0) ; cout.tie(0) ;
#define MOD (long long int)(1e9+7)
#define ll long long int
#define rep(i,n) for(int i=0; i<(int)(n); i++)
#define reps(i,n) for(int i=1; i<=(int)(n); i++)
#define REP(i,n) for(int i=n-1; i>=0; i--)
#define REPS(i,n) for(int i=n; i>0; i--)
#define INF (int)(1123456789)
#define LINF (long long int)(112345678901234567)
#define chmax(a, b) a = (((a)<(b)) ? (b) : (a))
#define chmin(a, b) a = (((a)>(b)) ? (b) : (a))
#define all(v) v.begin(), v.end()

typedef pair<int, int> Pii;
typedef pair<ll, ll> Pll;

ll mpow(ll a, ll b){
  if(b==0) return 1;
  else if(b%2==0){ll memo = mpow(a,b/2); return memo*memo%MOD;}
  else return mpow(a,b-1) * a % MOD;
}
ll lpow(ll a, ll b){
  if(b==0) return 1;
  else if(b%2==0){ll memo = lpow(a,b/2); return memo*memo;}
  else return lpow(a,b-1) * a;
}
ll gcd(ll a, ll b){
  if(b==0) return a;
  else return gcd(b, a%b);
}
vector<ll> kaijo_memo;
ll kaijo(ll n){
  if(kaijo_memo.size() > n) return kaijo_memo[n];
  if(kaijo_memo.size() == 0) kaijo_memo.push_back(1);
  while(kaijo_memo.size() <= n) kaijo_memo.push_back(kaijo_memo[kaijo_memo.size()-1] * kaijo_memo.size() % MOD);
  return kaijo_memo[n];
}
vector<ll> gyaku_kaijo_memo;
ll gyaku_kaijo(ll n){
  if(gyaku_kaijo_memo.size() > n) return gyaku_kaijo_memo[n];
  if(gyaku_kaijo_memo.size() == 0) gyaku_kaijo_memo.push_back(1);
  while(gyaku_kaijo_memo.size() <= n) gyaku_kaijo_memo.push_back(gyaku_kaijo_memo[gyaku_kaijo_memo.size()-1] * mpow(gyaku_kaijo_memo.size(), MOD-2) % MOD);
  return gyaku_kaijo_memo[n];
}

ll nCr(ll n, ll r){
  if(n == r) return 1;//0個の丸と-1個の棒みたいな時に時に効く？不安.
  if(n < r || r < 0) return 0;
  ll ret = 1;
  ret *= kaijo(n); ret %= MOD;
  ret *= gyaku_kaijo(r); ret %= MOD;
  ret *= gyaku_kaijo(n-r); ret %= MOD;
  return ret;
}

vector<Pll> G[1000], H[1000];
bool can_goal[1000] = {};
ll score[1000] = {};

void saiki(int now){
  if(can_goal[now]) return;
  can_goal[now] = true;
  rep(j,H[now].size()){
    int next = H[now][j].first;
    saiki(next);
  }
}

int main(void){
  fast_io
  cout<<fixed<<setprecision(15);

  ll n,m;cin>>n>>m;
  rep(i,m){
    ll a,b,c;cin>>a>>b>>c;a--;b--;
    G[a].push_back({b,c});
    H[b].push_back({a,c});
  }

  saiki(n-1);

  rep(i,n){
    if(!can_goal[i]){
      G[i].clear();
    }
    score[i] = -LINF;
  }
  score[0] = 0;

  rep(t_, 5000){
    ll score_next[1000] = {};
    rep(i,n){
      score_next[i] = score[i];
    }
    bool update = false;
    rep(i,n){
      if(score[i] == -LINF) continue;
      rep(j,G[i].size()){
        int next = G[i][j].first;
        int cost = G[i][j].second;
        if(score_next[next] < score[i] + cost){
          score_next[next] = score[i] + cost;
          update = true;
        }
      }
    }
    rep(i,n){
      score[i] = score_next[i];
    }
    if(!update){
      break;
    }
    if(t_ == 4999){
      cout<<"inf"<<endl;
      return 0;
    }
  }
  cout<<score[n-1]<<endl;
  return 0;
}

Measured memory_bytes: 512