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#include <bits/stdc++.h>
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;
}
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