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

map<string, int> mapp;

struct Edge{
    int to;
    double cost;
};
vector<Edge> v[20001];
int fl[20001];

bool ANS = false;

void Rec(int k, double tek) {
    if(fl[k] == 2) return;
    if(fl[k] == 1) {
        if(tek > 1) ANS = true;
        return;
    }
    fl[k] = 1;
    for(int i=0;i<v[k].size();i++) {
        Rec(v[k][i].to, tek*v[k][i].cost);
    }
    fl[k] = 2;
}

int main()
{
    freopen("trade.in", "r", stdin);
    freopen("trade.out", "w", stdout);
    cin.tie(NULL);
    int n, i, pos=0;
    scanf("%d", &n);
    for(i=1;i<=n;i++) {
        string s1, s2;
        double cost;
        cin>>s1>>s2;
        scanf("%lf", &cost);
        if(mapp[s1] == 0) mapp[s1] = ++pos;
        if(mapp[s2] == 0) mapp[s2] = ++pos;
        v[mapp[s1]].push_back({mapp[s2], cost});
    }

    for(i=1;i<=pos;i++) {
        fill(fl, fl+pos+1, 0);
        Rec(i, 1);
        if(ANS) break;
    }
    if(ANS) { printf("YES\n"); return 0; }

    for(i=1;i<=pos;i++) reverse(v[i].begin(), v[i].end());
    for(i=1;i<=pos;i++) {
        fill(fl, fl+pos+1, 0);
        Rec(i, 1);
        if(ANS) break;
    }


    if(ANS) printf("YES\n");
    else printf("NO\n");

    return 0;
}
/*
6
1 2 0.99
2 3 0.5
3 2 0.1
3 1 1.1
2 4 1.2
4 3 0.9
*/