#include <bits/stdc++.h>
using namespace std;
int main() {
  std::ios::sync_with_stdio(false);
  int n;
  cin >> n;
  string sign[n];
  long long x[n];
  char ans[n];
  long long low = -2e9, up = 2e9;
  for (int i = 0; i < n; i++) {
    cin >> sign[i] >> x[i] >> ans[i];
    if (sign[i] == ">=") {
      if (ans[i] == 'Y')
        low = max(low, x[i]);
      else
        up = min(x[i] - 1, up);
    } else if (sign[i] == ">") {
      if (ans[i] == 'Y')
        low = max(low, x[i] + 1);
      else
        up = min(x[i], up);
    } else if (sign[i] == "<=") {
      if (ans[i] == 'Y')
        up = min(x[i], up);
      else
        low = max(low, x[i] + 1);
    } else {
      if (ans[i] == 'Y')
        up = min(x[i] - 1, up);
      else
        low = max(low, x[i]);
    }
  }
  if (low > up)
    cout << "Impossible";
  else
    cout << low;
  return 0;
}
