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 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
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 *       notice, this list of conditions and the following disclaimer in the
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 *       to endorse or promote products derived from this software without 
 *       specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY XEHOTH AND CONTRIBUTORS "AS IS" AND ANY
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 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 ******************************************************************************/
#include <bits/stdc++.h>
/**
 * 「AtCoder Beginner Contest 061」 13-05-2017
 * @author xehoth 
 */
namespace IO {

inline char read() {
    static const int IN_LEN = 1000000;
    static char buf[IN_LEN], *s, *t;
    s == t ? t = (s = buf) + fread(buf, 1, IN_LEN, stdin) : 0;
    return s == t ? -1 : *s++;
}

template<class T>
inline void read(T &x) {
    static char c;
    static bool iosig;
    for (c = read(), iosig = false; !isdigit(c); c = read()) {
        if (c == -1) return;
        c == '-' ? iosig = true : 0;
    }
    for (x = 0; isdigit(c); c = read())
        x = (x + (x << 2) << 1) + (c ^ '0');
    iosig ? x = -x : 0;
}

const int OUT_LEN = 1000000;

char obuf[OUT_LEN], *oh = obuf;

inline void print(char c) {
    oh == obuf + OUT_LEN ? (fwrite(obuf, 1, OUT_LEN, stdout), oh = obuf) : 0;
    *oh++ = c;
}

template<class T>
inline void print(T x) {
    static int buf[30], cnt;
    if (x == 0) {
        print('0');
    } else {
        for (cnt = 0; x; x /= 10) buf[++cnt] = x % 10 | 48;
        while (cnt) print((char)buf[cnt--]);
    }
}

inline void flush() {
    fwrite(obuf, 1, oh - obuf, stdout);
}
}

namespace Task {

const int MAXN = 1010;

struct Node {
    int v;
    long long w;
    Node(int v, long long w) : v(v), w(w) {}
};

std::vector<Node> edge[MAXN];

inline void addEdge(const int u, const int v, const long long w) {
    edge[u].push_back(Node(v, w));
}

int num[MAXN], n;

long long dis[MAXN];

inline void spfa(int s) {
    static std::queue<int> q;
    static bool vis[MAXN];
    std::fill(dis, dis + n + 1, LLONG_MIN / 10);
    q.push(s), dis[s] = 0;
    register bool flag = false;
    register long long max = LLONG_MIN;
    register bool first = true;
    while (!q.empty()) {
        register int u = q.front();
        vis[u] = false, q.pop(), num[u]++;
        if (num[u] > n) {
            flag = true;
            break;
        }
        for (register int i = 0; i < edge[u].size(); i++) {
            Node *p = &edge[u][i];
            if (p->w + dis[u] > dis[p->v]) {
                dis[p->v] = p->w + dis[u];
                if (!vis[p->v]) {
                    if (p->v == n && first) {
                        max = dis[n], first = false;
                    }
                    q.push(p->v), vis[p->v] = true; 
                }
            }
        }
    }
    if (flag) {
        if (max == dis[n]) std::cout << dis[n] << "\n";
        else puts("inf");
        return;
    }
    std::cout << dis[n] << "\n";
}

inline void solve() {
    using namespace IO;
    register int m;
    read(n), read(m);
    register long long w;
    for (register int i = 0, u, v; i < m; i++) {
        read(u), read(v), read(w);
        addEdge(u, v, w);
    }
    spfa(1);
}
}

int main() {
#ifdef DBG
    freopen("in.in", "r", stdin);
#endif
    Task::solve();
    return 0;
}


Measured memory_bytes: 384