#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, a, n) for (ll i = a; i < (ll)n; ++i)
#define ENDL '\n'

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  ll n;
  cin >> n;
  ll tot = 0;
  map<string, vector<int>> ma;
  rep(i, 0, n) {
    string s, t;
    ll x;
    cin >> s >> t >> x;

    if (!ma.count(s))
      ma[s] = vector<int>(3, 0);
    if (t == "left")
      ma[s][0] += x;
    else if (t == "right")
      ma[s][1] += x;
    else
      ma[s][2] += x;
    tot += x;
  }

  ll ans = 0;
  for (auto &&p : ma) {
    auto v = p.second;
    ans += max({v[0], v[1], int(v[2] > 0)});
  }

  if (ans == tot)
    cout << "impossible" << ENDL;
  else
    cout << ans + 1 << ENDL;
}