#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
void read()
{
    freopen("trade.in","r",stdin);
    freopen("trade.out","w",stdout);
}
const int maxn = 10006;
ll i,j,p,q,n,m,k,koren,vr[maxn];
vector <pair<int,double>> v[maxn],g[maxn];
vector <int> obr[maxn];
map <string,int> act;
bool gfl;
vector <int> cyc;
string s,f;
bool comp[maxn];
int br;
bool b[maxn];
double raz[maxn];
double cur;
int Find(string s)
{
    if(act[s])
        return act[s];
    act[s] = ++br;
    return act[s];
}
void dfs(int u)
{
    comp[u] = true;
    b[u] = 1;
    for(auto i:obr[u])
    {
        if(!b[i])
            dfs(i);
    }
}
void dfs2(int u,double tek)
{
    raz[u] = tek;
    b[u] = 1;
    for(auto j:v[u])
    {
        p = j.first;
        double d = -j.second;
        if(b[p] && p==i)
        {
            double nt = tek*d;
            if(nt-raz[p]>0.0000001)
            {
                gfl=1;
                return ;
            }
            continue;
        }
        dfs2(p,tek*d);
    }
    raz[u] = 0;
    b[u] = 0;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    read();
    cin>>n;
    for(i=1;i<=n;i++)
    {
        cin>>s;
        cin>>f;
        cin>>cur;
        //cout<<s<<" "<<f<<" "<<cur<<endl;
        p = Find(s);
        q = Find(f);
        obr[q].push_back(p);
        g[p].push_back({q,-cur});
    }
    for(i=1;i<=n;i++)
    {
        sort(g[i].begin(),g[i].end());
        v[i].push_back(g[i][0]);
        for(j=1;j<g[i].size();j++)
        {
            if(g[i][j].first==g[i][j-1].first)
                continue;
            v[i].push_back(g[i][j]);
        }

    }
    if(act.find("BGN")==act.end())
    {
        cout<<"NO"<<endl;
        return 0;
    }
    koren = act["BGN"];
    dfs(koren);
    fill(b+1,b+n+1,0);
    for(i=1;i<=n;i++)
    {
        fill(b+1,b+n+1,0);
        //cyc.clear();
        gfl = 0;
        dfs2(i,1.0);
        if(gfl && comp[i])
        {
            cout<<"YES"<<endl;
            return 0;
        }
    }
    cout<<"NO"<<endl;
    return 0;
}