#include<bits/stdc++.h>
using namespace std;

#define rep(i,n) for(long long i=0;i<n;i++)
#define REP(i,s,n) for(long long i=(s);i<=(n);i++)
#define repr(i,n) for(long long i=n-1;i>=0;i--)
#define REPR(i,s,n) for(long long i=(s);i>=(n);i--)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define Eunique(v) v.erase(unique(all(v)),v.end())
#define Eback(s) s.erase(s.end()-1,s.end())
#define minvec(v) *min_element(all(v))
#define maxvec(v) *max_element(all(v))
#define sumvec(v) accumulate(all(v),0LL)
#define pb push_back
#define pf push_front
#define m_p make_pair
#define DOUBLE fixed << setprecision(15)
#define OK cerr<<"OK\n"
#define OK1 cerr<<"OK1\n"
#define OK2 cerr<<"OK2\n"
#define sz(s) (long long)s.size()
#define INF ((1LL<<62)-(1LL<<31))
#define zero(x,n) setw(x) << setfill('0') << n
//#define endl '\n'

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef vector<double> vd;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef vector<vd> vvd;
typedef vector<vc> vvc;
typedef vector<vb> vvb;
typedef pair<ll,ll> P;
typedef vector<P> vP;

template<class A, class B>
ostream& operator<<(ostream& ost, const pair<A, B>&p) {
	ost << "{" << p.first << ", " << p.second << "} ";
	return ost;
}

template<class T>
ostream& operator<<(ostream& ost, const vector<T>&v) {
	ost << "{";
	for (int i = 0; i<(int)v.size(); i++) {
		if (i)ost << " ";
		ost << v[i];
	}
	ost << "} \n";
	return ost;
}

template<class A, class B>
ostream& operator<<(ostream& ost, const map<A, B>&v) {
	ost << "{";
	for (auto p:v) {
		ost << "{" << p.first << ", " << p.second << "} ";
	}
	ost << "} ";
	return ost;
}

void out(){cout << "\n";}
template<class T,class... Args>
void out(const T &x,const Args &... args){
	cout << x << " ";
	out(args...);
}

template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
	for(T& e: vec) is >> e;
	return is;
}

template<typename T>
string join(vector<T>& vec, string sep=" "){
	stringstream ss;
	for(int i=0;i<(int)vec.size();i++){
		ss << vec[i] << (i+1==(int)vec.size()?"\n":sep);
	}
	return ss.str();
}

template<class T>
inline bool chmax(T& a, T b){if(a<b){a=b;return true;} return false;}

template<class T>
inline bool chmin(T& a, T b){if(a>b){a=b;return true;} return false;}

#define INT(...) int __VA_ARGS__;IN(__VA_ARGS__)
#define LL(...) long long __VA_ARGS__;IN(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;IN(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;IN(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;IN(__VA_ARGS__)
#define LD(...) long double __VA_ARGS__;IN(__VA_ARGS__)

void scan(int& a){ cin >> a; }
void scan(long long& a){ cin >> a; }
void scan(char& a){ cin >> a; }
void scan(double& a){ cin >> a; }
void scan(string& a){ cin >> a; }
void scan(long double& a){ cin >> a; }

void IN(){}
template<class Head,class... Tail> void IN(Head& head,Tail&... tail){ scan(head); IN(tail...); }

void YES(bool b) {cout << ((b)?"YES\n":"NO\n");}
void Yes(bool b) {cout << ((b)?"Yes\n":"No\n");}
void yes(bool b) {cout << ((b)?"yes\n":"no\n");}
void Yay(bool b) {cout << ((b)?"Yay!\n":":(\n");}

const long double pi = acos(-1.0);
const ll mod=1000000007;
//const ll mod=998244353;

ll powmod(ll a,ll b){ll c=1; while(b>0){ if(b&1){ c=a*c%mod; } a=a*a%mod; b>>=1; } return c;}
ll nCrmod(ll n,ll r){ll x=1,y=1; for(ll i=0;i<r;i++) {x=x*(n-i)%mod; y=y*(i+1)%mod; } return x*powmod(y,mod-2)%mod;}
ll gcd(ll a,ll b){ while(b){ ll c=b; b=a%b; a=c; } return a; }
ll lcm(ll a,ll b){ if(!a || !b) return 0; return a*b/gcd(a,b); }
vll divisor(ll x){ vll v; for(int i=1;i*i<=x;i++)if(x%i==0){ v.pb(i);if(i*i!=x)v.pb(x/i); } sort(all(v)); return v; };
map<ll,ll> prime_factor(ll n){ map<ll,ll> m; for(ll i=2;i*i<=n;i++){ while(n%i==0){ m[i]++; n/=i; } } if(n!=1) m[n]=1; return m; }

vvll to,rto;
vb from1,toN,both;

void dfs(ll v){
	if(from1[v]) return;
	from1[v]=true;
	for(auto&& u:to[v]) dfs(u);
}

void rdfs(ll v){
	if(toN[v]) return;
	toN[v]=true;
	for(auto&& u:rto[v]) rdfs(u);
}

int main()
{
	LL(n,m);
	to.resize(n);
	rto.resize(n);
	from1.resize(n);
	toN.resize(n);
	both.resize(n);
	vector<tuple<ll,ll,ll>> edges;
	rep(i,m){
		LL(a,b,c);
		a--;
		b--;
		c=-c;
		edges.emplace_back(a,b,c);
		to[a].push_back(b);
		rto[b].push_back(a);
	}
	dfs(0);
	rdfs(n-1);
	rep(i,n) both[i]=from1[i]&toN[i];

	vll d(n,INF);
	d[0]=0;
	bool upd=true;
	ll step=0;
	while(upd){
		upd=false;
		rep(i,m){
			ll a,b,c;
			tie(a,b,c)=edges[i];
			if(!both[a] || !both[b]) continue;
			ll newD=d[a]+c;
			if(newD<d[b]){
				upd=true;
				d[b]=newD;
			}
		}
		step++;
		if(step>n){
			cout << "inf\n";
			return 0;
		}
	}
	cout << -d[n-1] << endl;
	return 0;
}


Measured memory_bytes: 3808