#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(auto i = (a); i < (b); i++)
#define pb push_back
#define fs first
#define sc second
typedef long long ll;
typedef pair<int,int> ii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ii> vii;
typedef vector<vii> vvii;

const double EPS = 1e-9;

int main() {
    cin.sync_with_stdio(false);
    int n;
    cin >> n;
    map<pair<string,string>, int> TTS;
    set<string> TYPES;
    rep(i,0,n) {
        string a,b;
        int cnt = 0;
        cin >> a >> b >> cnt;
        TYPES.insert(a);
        TTS[pair<string,string>(a,b)] += cnt;
    }
    // check not possible
    bool can = false;
    for(auto a : TYPES) {
        string l = "left";
        string r = "right";
        string any = "any";
        int got_l = TTS[pair<string,string>(a,l)];
        int got_r = TTS[pair<string,string>(a,r)];
        int got_any = TTS[pair<string,string>(a,any)];
        if(got_l + got_any > 0 && got_r > 0) can = true;
        if(got_l > 0 && got_r + got_any > 0) can = true;
        if(got_any > 1) can = true;
    }
    if(!can) {
        cout << "impossible" << endl;
        return 0;
    }

    int total = 0;
    for(auto a : TYPES) {
        string l = "left";
        string r = "right";
        string any = "any";
        int got_l = TTS[pair<string,string>(a,l)];
        int got_r = TTS[pair<string,string>(a,r)];
        int got_any = TTS[pair<string,string>(a,any)];
        int mn = max(got_l, max(got_r, min(1, got_any)));
        total += mn;
    }
    cout << total+1 << endl;
}