#include <iostream>

using namespace std;

struct Trade {
    string name;
    string have;
    string want;
};

int main() {
    int n;
    cin >> n;

    struct Trade a[100];
    int y=1,z,w=0;
    string x;


    for(int i=0;i<n;i++){
        cin >> a[i].name >> a[i].have >> a[i].want;
        if(i>0)
            if(a[i].have == a[i-1].want){
                y++;
                if(y==2){
                    x=a[i-1].have;
                    z=i-1;
                }

            }else{
                if(a[i].want == x){
                    y++;
                }
                else{
                    z++;
                    x=a[z].have;
                    if(a[i].want==x)
                        y++;
                    else{
                        w=1;
                        break;
                    }

                }
            }

    }
    if(w!=1)
        cout << y;
    else
        cout << "No trades possible";

    return 0;
}