#include<bits/stdc++.h>
using namespace std;
void _main();int main(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(30);_main();return 0;}
typedef long long ll;typedef long double ld;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef string str;
#define rep1(a)          for(ll i = 0; i < (a); i++)
#define rep2(i, a)       for(ll i = 0; i < (a); i++)
#define rep3(i, a, b)    for(ll i = (a); i < (b); i++)
#define rep4(i, a, b, c) for(ll i = (a); i < (b); i += (c))
#define overload4(a, b, c, d, e, ...) e
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define ALL(x) std::begin(x),std::end(x)
#define rALL(x) std::rbegin(x),std::rend(x)
#define INF ((1LL<<62)-(1LL<<31))
#define inf ((1<<30)-(1<<15))
#define bit(x,i) (((x)>>(i))&1)
#define fi first
#define se second
#define pb push_back
#define Endl endl
#define spa " "
#define YesNo(x) cout<<(x?"Yes":"No")<<endl;
#define eps (1e-10)

//コンパイル時の引数にBLUEBERRYを渡すとdeb関数が使える
#ifdef BLUEBERRY
#define deb print
// #define _GLIBCXX_DEBUG
#else
#define deb(...)
//速くなる呪文
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#endif
//！？！？
#define O print
//可変長引数で入力を受け取りつつ変数を宣言
inline void scan(){}
template<class Head,class... Tail>
inline void scan(Head&head,Tail&... tail){std::cin>>head;scan(tail...);}
#define LL(...) ll __VA_ARGS__;scan(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;scan(__VA_ARGS__)
//vectorのcin
template<typename T>
std::istream &operator>>(std::istream&is,std::vector<T>&v){for(T &in:v){is>>in;}return is;}
//vectorのcout
template<typename T>
std::ostream &operator<<(std::ostream&os,const std::vector<T>&v){for(auto it=std::begin(v);it!=std::end(v);){os<<*it<<((++it)!=std::end(v)?" ":"");}return os;}
//pairのcin,cout
template<typename T,typename U>
std::ostream &operator<<(std::ostream&os,const std::pair<T,U>&p){os<<p.first<<" "<<p.second;return os;}
template<typename T,typename U>
std::istream &operator>>(std::istream&is,std::pair<T,U>&p){is>>p.first>>p.second;return is;}
//x,y,x,yを渡すとldで距離を返す
long double my_distance(long double xi,long double yi,long double xj,long double yj){return sqrt(abs((xi-xj)*(xi-xj))+abs((yi-yj)*(yi-yj)));}
//可変長引数のprint関数
#pragma GCC diagnostic ignored "-Wunused-value"
void print(){cout << '\n';}
template<class T, class... Ts>
void print(const T& a, const Ts&... b){cout << a;(std::cout << ... << (cout << ' ', b));cout << '\n';}
#pragma GCC diagnostic warning "-Wunused-value"
//可変長引数のmin
template<class... T>
constexpr auto min(T... a){return min(initializer_list<common_type_t<T...>>{a...});}
//可変長引数のmax
template<class... T>
constexpr auto max(T... a){return max(initializer_list<common_type_t<T...>>{a...});}
template<typename T,typename U>inline bool chmax(T&a,U b){if(a<b){a=b;return 1;}return 0;}
template<typename T,typename U>inline bool chmin(T&a,U b){if(a>b){a=b;return 1;}return 0;}
template<typename T> inline T sum(vector<T>&a){T ret{};for(auto&i:a)ret+=i;return ret;}
template<typename T> inline T min(vector<T>&a){T ret=a[0];for(auto&i:a)chmin(ret,i);return ret;}
template<typename T> inline T max(vector<T>&a){T ret=a[0];for(auto&i:a)chmax(ret,i);return ret;}
template<typename T> inline int len(vector<T>&a){return a.size();}
inline int len(string&a){return a.size();}
// n次元配列の初期化。第２引数の型のサイズごとに初期化していく。
template<typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val){std::fill( (T*)array, (T*)(array+N), val );}
//こめんとを付け外ししてMODを切り替える
//ll MOD = INF;
// ll MOD = 1000000007;
ll MOD = 998244353;
pair<long long, long long> extgcd(long long a, long long b) {
  if (b == 0) return make_pair(1, 0);
  long long x, y;
  tie(y, x) = extgcd(b, a % b);
  y -= a / b * x;
  return make_pair(x, y);
}

struct Rande {mt19937 mt;Rande(): mt(chrono::steady_clock::now().time_since_epoch().count()){}int operator()(int a, int b) {uniform_int_distribution< int > dist(a, b - 1);return dist(mt);}int operator()(int b){return (*this)(0, b);}};
//from:https://kenkoooo.hatenablog.com/entry/2016/11/30/163533 int128
std::ostream &operator<<(std::ostream &dest, __int128_t value) {std::ostream::sentry s(dest);if (s){__uint128_t tmp = value < 0 ? -value : value;char buffer[128];char *d = std::end(buffer);do{--d;*d = "0123456789"[tmp % 10];tmp /= 10;} while (tmp != 0);if (value < 0) {--d;*d = '-';}int len = std::end(buffer) - d;if (dest.rdbuf()->sputn(d, len) != len) {dest.setstate(std::ios_base::badbit);}}return dest;}
__int128 parsetoint128(string &s) {__int128 ret = 0;for (int i = 0; i < (int)s.length(); i++)if ('0' <= s[i] && s[i] <= '9')ret=10*ret+(__int128_t)(s[i]-'0');return ret;}

ll divide(ll a, ll b){if(b < 0) a *= -1, b *= -1;if(a >= 0) return a/b;else return -(((-a)+(b-1))/b);}
//回文判定 
bool iskaibun(string s){ll k = s.size();rep(i,0,k/2){if(s[i]!=s[k-1-i]){return false;}}return true;}

//二部グラフ判定 重みなしグラフを引数に取り、boolを返す
bool isbipartite_graph(vector<vector<ll>>&g){ll v = g.size();vector<ll>col(v,-1);vector<bool>used(v,false);bool ret = true;rep(i,v){if(used[i])continue;col[i]=0;[DFS([&](auto&&f,ll pos,ll pr)->void{if(used[pos])return;used[pos]=true;for(auto to:g[pos]){if(to==pr)continue;if(used[to]&&col[pos]==col[to]){ret = false;return;}if(used[to])continue;col[to]=col[pos]^1;f(f,to,pos);}}),&i]{DFS(DFS,i,-1);}();}return ret;}
//a~bの和 a<b
ll ran(ll a,ll b){return ((a+b)*(b-a+1))/2;}
//座圧する
ll zaatu(vector<ll>&A){map<ll,ll>m;for(auto&&x:A)m[x]=0;ll ret = 0;for(auto&&[key,val]:m)val=ret++;for(auto&&x:A)x=m[x];return ret;}
//約数列挙　引数に取った整数の約数のvectorを返す
vector<ll>enumdiv(ll n){vector<ll>s;for(ll i = 1;i*i<=n;i++){if(n%i==0){s.push_back(i);if(i*i!=n)s.push_back(n/i);}}return s;}
//トポロジカルソート グラフ、入次数カウント、頂点数を引数で渡すと、トポロジカルソートされた頂点列を返す
vector<ll> topo_sort(vector<vector<ll>>&G,vector<ll>&nyu_cnt,ll v){vector<ll>ret;priority_queue<ll,vector<ll>,greater<ll>>pq;rep(i,0,v){if(nyu_cnt[i]==0)pq.push(i);}while(!pq.empty()){ll pos = pq.top();pq.pop();for(ll i:G[pos]){nyu_cnt[i]--;if(nyu_cnt[i]==0)pq.push(i);}ret.push_back(pos);}return ret;}
//素因数分解 pair<素数、指数>のvectorを返す
vector<pair<ll,ll>> soinsu_bunkai(ll x){vector<pair<ll,ll>>ret;rep(i,2,sqrt(x)+1){if(x%i==0){ll cnt{};while(x%i==0){x/=i;cnt++;}ret.push_back({i,cnt});}}if(x!=1)ret.push_back({x,1});return ret;}
//二項係数MOD MODは上の方で設定、MAXまでのnCrをCOM(n,r)でとれる
const int MAX = 5000010;
ll fac[MAX], finv[MAX], invv[MAX];
void COMinit(){fac[0]=fac[1]=finv[0]=finv[1]=invv[1]=1;for(int i=2;i<MAX;i++){fac[i]=fac[i-1]*i%MOD;invv[i]=MOD-invv[MOD%i]*(MOD/i)%MOD;finv[i]=finv[i-1]*invv[i]%MOD;}}
ll COM(int n,int k){if(n<k)return 0;if(n<0||k<0)return 0;if(k==0)return 1;return fac[n]*(finv[k]*finv[n-k]%MOD)%MOD;}
ll nPr(int n,int k){if(n<k)return 0;if(n<0||k<0)return 0;if(k==0)return 1;return fac[n]*(finv[n-k]);}
//エラトステネスの篩　isprimeには素数かどうかが入っている
vector<bool> isprime;vector<int> Era(int n) {isprime.resize(n, true);vector<int> res;isprime[0] = false; isprime[1] = false;for (int i = 2; i < n; ++i) isprime[i] = true;for (int i = 2; i < n; ++i){if (isprime[i]) {res.push_back(i);for (int j = i*2; j < n; j += i) isprime[j] = false;}}return res;}
//Union-Find from https://zenn.dev/reputeless/books/standard-cpp-for-competitive-programming/viewer/union-find
class UnionFind{public:UnionFind()=default;explicit UnionFind(size_t n):m_parentsOrSize(n, -1){}int find(int i){if(m_parentsOrSize[i]<0){return i;}return(m_parentsOrSize[i]=find(m_parentsOrSize[i]));}void merge(int a,int b){a=find(a);b=find(b);if(a!=b){if(-m_parentsOrSize[a]<-m_parentsOrSize[b]){std::swap(a,b);}m_parentsOrSize[a]+=m_parentsOrSize[b];m_parentsOrSize[b]=a;}}bool connected(int a,int b){return (find(a)==find(b));}int size(int i){return -m_parentsOrSize[find(i)];}private:std::vector<int>m_parentsOrSize;};
template <class T> using pqg = priority_queue<T, vector<T>, greater<T>>;
template <class F> ll bin_search(ll ok,ll ng,const F&f){while(abs(ok-ng)>1){long long mid=(ok+ng)>>1;(f(mid)?ok:ng)=mid;}return ok;}
//グリッドの8近傍 4まで回せば4近傍
ll dx[8] = {0,1,0,-1,-1,-1,1,1},dy[8]={1,0,-1,0,-1,1,-1,1};


bool solve();
void _main(){
[]{[]{[]{[]{[]{}();}();}();}();}();
	int testcase = 1;
	// cin >> testcase,cerr<<"multitestcase"<<endl;
	for(;testcase--;){
		if(solve()){
			// O("Yes");
		}
		else{
			// O(-1);
			// O("No");
		}
	}
	cout<<flush;
[]{[]{[]{[]{[]{}();}();}();}();}();
}
// #include<atcoder/modint>
// using namespace atcoder;
// using mint = modint;
// using mint = modint998244353;
// using mint = modint1000000007;
// std::ostream &operator<<(std::ostream&os,const mint x){os<<x.val();return os;}template<typename T1, typename T2>std::ostream &operator<< (std::ostream &os, std::pair<T1,T2> p){os << "{" << p.first << "," << p.second << "}";return os;}
struct Edge
{
	ll from;
	ll to;
	ll cost;
};
bool BellmanFord(const std::vector<Edge>& edges, std::vector<long long>& distances, int startIndex)
{

	for (size_t i = 0; i < distances.size(); ++i)
	{
		bool changed = false;

		// 各辺について
		for (const auto& edge : edges)
		{
			// (INF + cost) は INF なので処理しない
			if (distances[edge.from] == INF)
			{
				continue;
			}

			// to までの新しい距離
			const long long d = (distances[edge.from] + edge.cost);

			// d が現在の記録より小さければ更新
			if (d < distances[edge.to])
			{
				distances[edge.to] = d;

				changed = true;
			}
		}

		// どの頂点も更新されなかったら終了
		if (!changed)
		{
			return false;
		}
	}

	// 頂点数分だけさらに繰り返し, 負閉路の影響を受ける頂点に -INF を伝播
	for (size_t i = 0; i < distances.size(); ++i)
	{
		for (const auto& edge : edges)
		{
			if (distances[edge.from] == INF)
			{
				continue;
			}

			const long long d = (distances[edge.from] + edge.cost);

			if (d < distances[edge.to])
			{
				// 負閉路の影響を受ける頂点を -INF に
				distances[edge.to] = -INF;
			}
		}
	}

	return true;
}

bool solve(){
	LL(n,m);
	vector<ll>a(n);cin >> a;
	vector<Edge>edges;
	rep(i,m){
		LL(A,B,C);
		A--,B--;
		edges.push_back({A,B,(C-a[B])});
	}
	vector<ll>dist(n,INF);
	dist[0] = -a[0];
	if(BellmanFord(edges,dist,0)){
		if(dist[n-1]<=-INF)O("inf");
		else O(-dist[n-1]);
	}
	else{
		O(-dist[n-1]);
	}
	return true;
}