#include using namespace std; #define rep(i,n) for(ll i=0;i=0;i--) #define perl(i,r,l) for(ll i=r-1;i>=l;i--) #define fi first #define se second #define pb push_back #define ins insert #define pqueue(x) priority_queue,greater> #define all(x) (x).begin(),(x).end() #define CST(x) cout<; using vvl=vector>; using pl=pair; using vpl=vector; using vvpl=vector; const ll MOD=1000000007; const ll MOD9=998244353; const int inf=1e9+10; const ll INF=4e18; const ll dy[8]={-1,0,1,0,1,1,-1,-1}; const ll dx[8]={0,-1,0,1,1,-1,1,-1}; template inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } struct edge{ ll to,len,num; }; vl topsort(vvl &g){ ll n=g.size(); vl ans,ind(n); rep(i,n)for(auto e:g[i])ind[e]++; queue que; rep(i,n)if(!ind[i])que.push(i); while(!que.empty()){ ll v=que.front();que.pop(); ans.pb(v); for(auto nv:g[v]){ ind[nv]--;if(!ind[nv])que.push(nv); } } return ans; } const int mod = 1000000007; const int max_n = 200005; struct mint { ll x; // typedef long long ll; mint(ll x=0):x((x%mod+mod)%mod){} mint operator-() const { return mint(-x);} mint& operator+=(const mint a) { if ((x += a.x) >= mod) x -= mod; return *this; } mint& operator-=(const mint a) { if ((x += mod-a.x) >= mod) x -= mod; return *this; } mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;} mint operator+(const mint a) const { return mint(*this) += a;} mint operator-(const mint a) const { return mint(*this) -= a;} mint operator*(const mint a) const { return mint(*this) *= a;} mint pow(ll t) const { if (!t) return 1; mint a = pow(t>>1); a *= a; if (t&1) a *= *this; return a; } bool operator==(const mint &p) const { return x == p.x; } bool operator!=(const mint &p) const { return x != p.x; } // for prime mod mint inv() const { return pow(mod-2);} mint& operator/=(const mint a) { return *this *= a.inv();} mint operator/(const mint a) const { return mint(*this) /= a;} }; istream& operator>>(istream& is, mint& a) { return is >> a.x;} ostream& operator<<(ostream& os, const mint& a) { return os << a.x;} int main(){ ll n,m;cin >> n >>m; vector> g(n+1); vvl t(n+1); rep(i,m){ ll a,b,c,d;cin >> a >> b >> c >> d; g[a].pb({b,c,d}); t[a].pb(b); } auto ord=topsort(t); if(ord.size()!=n+1){ cout << "INF" <> dp(n+1); dp[0]={0,1}; rep(i,n+1){ ll now=ord[i]; for(auto p:g[now]){ dp[p.to].fi+=(dp[now].fi+dp[now].se*p.len)*p.num; dp[p.to].se+=dp[now].se*p.num; } } cout << dp[n].fi <