/*
 * author:  ADMathNoob
 * created: 05/07/24 20:14:29
 * problem: https://qoj.ac/problem/2302#tab-statement
 */

/*
Comments about problem:


*/

#include <bits/stdc++.h>

using namespace std;

#ifdef _DEBUG
#include "debug.h"
#else
#define debug(...) 42
#endif

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  map<string, map<string, int>> mp;
  int k;
  cin >> k;
  for (int i = 0; i < k; i++) {
    string s, t;
    int x;
    cin >> s >> t >> x;
    mp[s][t] = x;
  }
  bool ok = false;
  int ans = 0;
  for (auto [_, mp1] : mp) {
    int L = mp1["left"];
    int R = mp1["right"];
    int a = mp1["any"];
    if (a >= 2 || (a == 1 && L + R >= 1) || (L >= 1 && R >= 1)) {
      ok = true;
    }
    int add = max(L, R);
    if (a >= 1) {
      add = max(add, 1);
    }
    ans += add;
  }
  if (ok) {
    cout << ans + 1 << '\n';
  } else {
    cout << "impossible\n";
  }
  return 0;
}