#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x, y, large = 2000000000, small = -2000000000;
  string s1, s2;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> s1 >> x >> s2;
    if ((s1 == ">" && s2 == "Y") || (s1 == "<=" && s2 == "N")) {
      if (x >= small) {
        small = x + 1;
      }
    } else if ((s1 == "<" && s2 == "Y") || (s1 == ">=" && s2 == "N")) {
      if (x <= large) {
        large = x - 1;
      }
    } else if ((s1 == ">=" && s2 == "Y") || (s1 == "<" && s2 == "N")) {
      if (x >= small) {
        small = x;
      }
    } else {
      if (x <= large) {
        large = x;
      }
    }
  }
  if (small > large) {
    cout << "Impossible";
  } else {
    cout << small;
  }
  return (0);
}
