#include<bits/stdc++.h>
using namespace std;
struct cost{
    int to;
    bool direct;
    double price;
    cost(){}
    cost(int _to, bool _direct, double _price){
        to = _to;
        direct = _direct;
        price = _price;
    }
};
const int maxn = 1e4 + 10;
map<string, int> currency;
vector<cost> v[maxn];
int n, used[maxn], used1[maxn], used2[maxn], X1;
bool infmoney[maxn];
double money[maxn];
inline void get_num_from_map(int &num, string &s){
    if(currency.find(s) == currency.end())
        currency[s] = currency.size() + 1;
    num = currency[s];
}
void make_component_profit(int ver){
    used2[ver] = 1;
    infmoney[ver] = true;
    //if()
    for (auto nb: v[ver])
        if (!used2[nb.to])
            make_component_profit(nb.to);
}
void DFS(int ver){
    used[ver] = 1;
    used1[ver] = 1;
    for (auto nb: v[ver]){
        double curmoney;
        if (!used1[nb.to]){
            curmoney = money[nb.to];
            money[nb.to] = (nb.direct == true)? money[ver]*nb.price: money[ver]/nb.price;
            DFS(nb.to);
            money[nb.to] = curmoney;
        }
        else{
            double curmoney = (nb.direct == true)? money[ver]*nb.price: money[ver]/nb.price;
            if (curmoney > money[nb.to]){
                cout << "YES\n";
                exit(0);
            }
        }
    }
    used1[ver] = 0;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	cin >> n;
	for (int i = 0; i < n; ++i){
        string s1, s2;
        double price;
        cin >> s1 >> s2 >> price;
        int n1, n2;
        get_num_from_map(n1, s1);
        get_num_from_map(n2, s2);
        v[n1].push_back(cost(n2, true, price));
        v[n2].push_back(cost(n1, false, price));
	}
	X1 = currency["BGN"];
	money[X1] = 1;
	DFS(1);
	cout << "NO\n";
return 0;
}