#include <bits/stdc++.h>
using namespace std;
int n, b;
string a, c;
int main() {
  cin >> n;
  int l = -2e9, r = 2e9;
  for (; n--;) {
    cin >> a >> b >> c;
    if (a == ">" && c == "Y" || a == "<=" && c == "N")
      l = max(l, b + 1);
    else if (a == ">=" && c == "Y" || a == "<" && c == "N")
      l = max(l, b);
    else if (a == "<" && c == "Y" || a == ">=" && c == "N")
      r = min(r, b - 1);
    else
      r = min(r, b);
  }
  if (l > r)
    puts("Impossible");
  else
    printf("%d", l);
}
