#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <iomanip>
using ll = long long;
using uint = unsigned int;
using graph = std::vector<std::vector<ll>>;
using wGraph = std::vector<std::vector<std::pair<ll,ll>>>;
#define rep(i,n) for (int i=0; i < int(n); i++)

using namespace std;
ll MOD7 = 1000000007;
ll MOD9 = 1000000009;
vector<ll> InputVec(ll N){
    vector<ll> A(N);
    for (int i = 0; i < N; ++i) {
        cin >> A[i];
    }
    return A;
}
void OutputVec(vector<ll> A){
    for (int i = 0; i < A.size(); ++i) {
        cout << A[i] << ",";
    }
    cout << endl;
}
void OutputVec(vector<bool> A){
    for (int i = 0; i < A.size(); ++i) {
        cout << A[i] << ",";
    }
    cout << endl;
}
vector<vector<ll>> InputVec2d(ll H,ll W){
    vector<vector<ll>> A(H);
    for (int yi = 0; yi < H; ++yi) {
        A[yi] = vector<ll>(W);
    }
    for (int yi = 0; yi < H; ++yi) {
        for (int xi = 0; xi < W; ++xi) {
            cin >> A[yi][xi];
        }
    }
    return A;
}
vector<vector<char>> InputVec2dStr(ll H,ll W){
    vector<vector<char>> A(H);
    for (int yi = 0; yi < H; ++yi) {
        A[yi] = vector<char>(W);
    }
    for (int yi = 0; yi < H; ++yi) {
        string S;
        cin >> S;
        for (int xi = 0; xi < W; ++xi) {
            A[yi][xi] = S[xi];
        }
    }
    return A;
}
void OutputVec2d(vector<vector<ll>> A){
    for (int yi = 0; yi < A.size(); ++yi) {
        for (int xi = 0; xi < A[yi].size(); ++xi) {
            cout << A[yi][xi] << ",";
        }
        cout << endl;
    }
}
graph InputGraph(ll N,ll M){
    graph G(N);
    for (int i = 0; i < M; ++i) {
        ll a,b;
        cin >> a >> b;
        a--;b--;
        G[a].push_back(b);
        G[b].push_back(a);
    }
    return G;
}
graph InputDGraph(ll N,ll M){
    graph G(N);
    for (int i = 0; i < M; ++i) {
        ll a,b;
        cin >> a >> b;
        a--;b--;
        G[a].push_back(b);
    }
    return G;
}
wGraph InputWGraph(ll N,ll M, bool isNeg){
    wGraph G(N);
    for (int i = 0; i < M; ++i) {
        ll a,b,c;
        cin >> a >> b >> c;
        a--;b--;
        if(isNeg){
            c = -c;
        }
        G[a].push_back(make_pair(b,c));
        G[b].push_back(make_pair(a,c));
    }
    return G;
}
wGraph InputDWGraph(ll N, ll M,bool isNeg){
    wGraph G(N);
    for (int i = 0; i < M; ++i) {
        ll a,b,c;
        cin >> a >> b >> c;
        a--;b--;
        if(isNeg){
            c = -c;
        }
        G[a].push_back(make_pair(b,c));
    }
    return G;
}
void OutputGraph(graph G){
    for (int i = 0; i < G.size(); ++i) {
        cout << i << ":";
        for (int j = 0; j < G[i].size(); ++j) {
            cout << G[i][j]<< ",";
        }
        cout << endl;
    }
}

void OutputGraph(wGraph G){
    for (int i = 0; i < G.size(); ++i) {
        cout << i << ":";
        for (int j = 0; j < G[i].size(); ++j) {
            cout << G[i][j].first <<"/" << G[i][j].second << ",";
        }
        cout << endl;
    }
}

void OutputAnswerBool(bool b,bool isUpperCase = false){
    if(b){
        if(isUpperCase){
            cout << "YES" << endl;
        }else{
            cout << "Yes" << endl;
        }
    }else{
        if(isUpperCase){
            cout << "NO" << endl;
        }else{
            cout << "No" << endl;
        }
    }
}

vector<ll> Bellman_Ford(wGraph& G,ll s,ll t,ll N,vector<bool>& has_negloop){
    ll MAX = 1ll << 50;
    vector<ll>d(N,MAX);
    d[s] = 0;
    auto seen = vector<bool>(N,false);
    seen[0] = true;
    for (int i = 0; i < N-1; ++i) {
        for (int j = 0; j < N; ++j) {
            for (int k = 0; k < G[j].size(); ++k) {
                auto current = G[j][k];
                if(seen[j]){
                    seen[current.first] = true;
                }
                if(d[j] + current.second < d[current.first]){
                    d[current.first] = d[j] + current.second;
                }
            }
        }
    }
    has_negloop = vector<bool>(N,false);
    for (int i = 0; i < N; ++i) {
        for (int j = 0; j < N; ++j) {
            for (int k = 0; k < G[j].size(); ++k) {
                auto current = G[j][k];
                if(has_negloop[j]){
                    if(seen[j]){
                        has_negloop[current.first] = true;
                    }
                }
                if(d[j] + current.second < d[current.first]){
                    d[current.first] = d[j] + current.second;
                    if(seen[j]){
                        has_negloop[current.first] = true;
                    }
                }
            }
        }
    }
    return d;
}

int main() {
    ll N,M;
    cin >> N >> M;
    auto G = InputDWGraph(N,M, true);
    vector<bool> neg;
    auto d = Bellman_Ford(G,0,N-1,N,neg);
    //OutputVec(neg);
    //OutputVec(d);
    if(neg[N-1]){
        cout << "inf" << endl;
        return 0;
    }
    cout << -d[N-1] << endl;
}


Measured memory_bytes: 3668