#include<bits/stdc++.h>
using namespace std;
#define sc(a) scanf("%d", &a)
#define sc2(a, b) scanf("%d%d", &a, &b)
#define sc3(a, b, c) scanf("%d%d%d", &a, &b, &c)
#define scs(a) scanf("%s", a)
#define pri(x) printf("%d\n", x)
#define prie(x) printf("%d ", x)
#define pris() printf("\n")
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define BUFF ios::sync_with_stdio(false)
#define db(x) cerr << #x << " == " << x << endl
#define power(a,x) __gnu_cxx::power(a, x)
#define eps 1e-5
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<vector<int> > vvi;
typedef vector<ii> vii;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fll;
const ld pi = acos(-1);
const int MOD = 1e9 + 7;
map<string,double> dp;
int main()
{
    BUFF;
    int n;
    cin>>n;
    dp["pink"]=1;
    while(n--)
    {
        string a,b;
        cin>>a>>b;
        double x;
        cin>>x;
        if(dp.count(a)){
            double y = 0;
            if(dp.count(b) ) y = log(dp[b]);
            dp[a]=min(max(log2(dp[a]),log2(y)+log2(x)),(double)INF);
        }else{
            dp[a] = log2(x);
        }
    }
    cout<<setprecision(15)<<fixed;
    dp["blue"]=min((double)10,pow(dp["blue"], 2) );
    cout<<dp["blue"]<<endl;
    return 0;
}