/*
 * じょえチャンネル
 * 高評価・チャンネル登録よろしくおねがいします！
 * https://www.youtube.com/channel/UCRXsI3FL_kvaVL9zoolBfbQ
 */

#include <bits/stdc++.h>

//#pragma GCC target("avx2")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")

#define f(i, n) for (int i = 0; i < (n); i++)

#define inf (int)(3e18)

//here!!!
// define int long long !!!!!

#define int long long

// define int long long !!!!!

#define mod (int)((1e9) + 7)
//constexpr int mod = 998244353ll;

#define intt long long
#define itn long long
#define P pair<int, int>

#define rep(i, n) for (int i = 0; i < n; i++)
#define REP(i, n) for (int i = 1; i <= n; i++)

#define ALL(v) v.begin(), v.end()

using namespace std;

//Library
//モッドパウ
inline int modpow(int x, int y, int m = mod) {
    int res = 1;
    while (y) {
        if (y % 2) {
            res *= x;
            res %= m;
        }
        x = x * x % m;
        y /= 2;
    }
    return res;
}

int mypow(int x, int y) {
    int res = 1;
    while (y) {
        if (y % 2) {
            res *= x;
        }
        x = x * x;
        y /= 2;
    }
    return res;
}
//is the number (x) a prime number?
bool prime(int x) {
    for (int i = 2; i * i <= x; i++) {
        if (!(x % i)) {
            return false;
        }
    }
    return true;
}

//saidai-kouyakusuu
inline int gcd(int x, int y) {
    if (!y) {
        return x;
    }
    return gcd(y, x % y);
}

//number of keta
int keta(int x) {
    int ans = 0;
    while (x) {
        x /= 10;
        ans++;
    }
    return ans;
}

//sum of keta
int ketasum(int x) {
    int ans = 0;
    while (x) {
        ans += x % 10;
        x /= 10;
    }
    return ans;
}

inline int lcm(int x, int y) {
    int ans = x / gcd(x, y) * y;
    return ans;
}
int twobeki(int x) {
    int ans = 0;
    while (1) {
        if (!(x & 1)) {
            ans++;
            x /= 2;
        } else {
            break;
        }
    }
    return ans;
}

template <class T, class U>
inline bool chmax(T &lhs, const U &rhs) {
    if (lhs < rhs) {
        lhs = rhs;
        return 1;
    }
    return 0;
}
template <class T, class U>
inline bool chmin(T &lhs, const U &rhs) {
    if (lhs > rhs) {
        lhs = rhs;
        return 1;
    }
    return 0;
}
void Yes() {
    cout << "Yes" << endl;
}
void No() {
    cout << "No" << endl;
}
void YES() {
    cout << "YES" << endl;
}
void NO() {
    cout << "NO" << endl;
}

#define fin(i) scanf("%lld", &i)
#define fout(i) printf("%lld", i)
#define fendl printf("\n")

int kai(int x, int y) {
    int res = 1;
    for (int i = x - y + 1; i <= x; i++) {
        res *= i;
        res %= mod;
    }
    return res;
}

int comb(int x, int y) {
    if (y > x)
        return 0;
    //    cout<<kai(x, y)<<' '<<modpow(kai(y, y), mod - 2)<<endl;
    return kai(x, y) * modpow(kai(y, y), mod - 2) % mod;
}
//Library-End

#define vecin(v)                       \
    for (int i = 0; i < v.size(); i++) \
        scanf("%lld", &v[i]);
#define vecout(v)                               \
    {                                           \
        for (int i = 0; i < (int)v.size(); i++) \
            printf("%lld ", v[i]);              \
        printf("\n");                           \
    }

//SegTree
template <class T>
class SegTree {
    int n;                       // 葉の数
    vector<T> data;              // データを格納するvector
    T def;                       // 初期値かつ単位元
    function<T(T, T)> operation; // 区間クエリで使う処理
    function<T(T, T)> update;    // 点更新で使う処理

    // 区間[a,b)の総和。ノードk=[l,r)に着目している。
    T _query(int a, int b, int k, int l, int r) {
        if (r <= a || b <= l)
            return def; // 交差しない
        if (a <= l && r <= b)
            return data[k]; // a,l,r,bの順で完全に含まれる
        else {
            T c1 = _query(a, b, 2 * k + 1, l, (l + r) / 2); // 左の子
            T c2 = _query(a, b, 2 * k + 2, (l + r) / 2, r); // 右の子
            return operation(c1, c2);
        }
    }

public:
    // _n:必要サイズ, _def:初期値かつ単位元, _operation:クエリ関数,
    // _update:更新関数
    SegTree(size_t _n, T _def, function<T(T, T)> _operation,
            function<T(T, T)> _update)
        : def(_def), operation(_operation), update(_update) {
        n = 1;
        while (n < _n) {
            n *= 2;
        }
        data = vector<T>(2 * n - 1, def);
    }

    // 場所i(0-indexed)の値をxで更新
    void change(int i, T x) {
        i += n - 1;
        data[i] = update(data[i], x);
        while (i > 0) {
            i = (i - 1) / 2;
            data[i] = operation(data[i * 2 + 1], data[i * 2 + 2]);
        }
    }

    // [a, b)の区間クエリを実行
    T query(int a, int b) {
        return _query(a, b, 0, 0, n);
    }

    // 添字でアクセス
    T operator[](int i) {
        return data[i + n - 1];
    }
};

#define R_MIN ([](long long a, long long b) { return min(a, b); })
#define R_MAX ([](long long a, long long b) { return max(a, b); })
#define R_SUM ([](long long a, long long b) { return a + b; })

#define NORMAL_UPDATE ([](long long a, long long b) { return b; })
#define ADD_UPDATE ([](long long a, long long b) { return a + b; })
#define MINUS_UPDATE ([](long long a, long long b) { return a - b; }

class Union_Find {
    vector<int> par;
    vector<int> rankmy;
    vector<int> ookisa;

public:
    Union_Find(int size) {
        par = vector<int>(size);
        rankmy = vector<int>(size);
        ookisa = vector<int>(size);
        for (int i = 0; i < size; i++) {
            par[i] = i;
            ookisa[i] = 1;
        }
    }

    int find(int x) {
        if (par[x] == x) {
            return x;
        }
        return par[x] = find(par[x]);
    }

    void unite(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) {
            return;
        }
        if (rankmy[x] < rankmy[y]) {
            par[x] = y;
            ookisa[y] += ookisa[x];
            ookisa[x] = 0;
        } else {
            par[y] = x;
            ookisa[x] += ookisa[y];
            ookisa[y] = 0;
            if (rankmy[x] == rankmy[y]) {
                rankmy[x]++;
            }
        }
    }
    int size(int i) {
        i = find(i);
        return ookisa[i];
    }
    bool same(int x, int y) {
        return find(x) == find(y);
    }
};

//Union-Find-End
#define endl "\n" //interactive の時に注意！！！
int perm[1000005];
void init_perm() {
    perm[0] = 1;
    REP(i, 1000000) {
        perm[i] = perm[i - 1] * i % mod;
    }
}

int nCk(int x, int y) {
    return perm[x] * modpow(perm[x - y], mod - 2) % mod * modpow(perm[y], mod - 2) % mod;
}

double kyori(pair<int, int> f, pair<int, int> s) {
    double ans = 0;
    double t = fabs(f.first - s.first);
    double y = fabs(f.second - s.second);
    ans = sqrt(t * t + y * y);
    return ans;
}

inline string stringmax(string &x, string &y) {
    if (x.size() > y.size()) {
        return x;
    }
    if (x.size() < y.size()) {
        return y;
    }
    rep(i, x.size()) {
        if (x[i] > y[i]) {
            return x;
        }
        if (x[i] < y[i]) {
            return y;
        }
    }
    return x;
}

itn n, m, p, a[5004], b[5004], c[5004];
vector<P> road[3004];
vector<int> gya[3004];
int kyo[3004];
int cnt[3004];
bool tsu[3004];

void dfs(int x) {
    tsu[x] = 1;
    for (auto &i : gya[x]) {
        if (tsu[i]) {
            continue;
        }
        dfs(i);
    }
}
signed main() {
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    cin >> n >> m;
    rep(i, m) {
        cin >> a[i] >> b[i] >> c[i];
        gya[b[i]].emplace_back(a[i]);
    }
    dfs(n);
    rep(i, m) {
        if (tsu[a[i]] && tsu[b[i]]) {
            road[a[i]].emplace_back(b[i], c[i]);
        }
    }
    REP(i, n)
    kyo[i] = 0 - inf;
    kyo[1] = 0;
    priority_queue<P> p;
    p.push({0, 1});
    while (p.size()) {
        P x = p.top();
        p.pop();

        cnt[x.second]++;
        for (auto &i : road[x.second]) {
            if (kyo[x.second] + i.second > kyo[i.first]) {
                if (cnt[i.first] > n) {
                    cout << "inf" << endl;
                    return 0;
                }
                p.push({kyo[x.second] + i.second, i.first});
                kyo[i.first] = kyo[x.second] + i.second;
            }
        }
    }
    cout << kyo[n] << endl;
}


Measured memory_bytes: 1276