#include <bits/stdc++.h>
using namespace std;
int n, m, t, k;
long long l[10005], r[10005];
int x[10005];
char s1[10005][11], s2[10005][11];
int main() {
  scanf("%d", &n);
  long long lx = -2 * 1000000000, ly = 2 * 1000000000;
  l[0] = -2 * 1000000000;
  r[0] = 2 * 1000000000;
  int flag = 1;
  for (int i = 1; i <= n; i++) {
    scanf("%s%d%s", s1[i], &x[i], s2[i]);
    if (s2[i][0] == 'N') {
      if (s1[i][0] == '<') {
        s1[i][0] = '>';
        if (s1[i][1] == '=')
          s1[i][1] = '\0';
        else
          s1[i][1] = '=';
      } else {
        if (s1[i][0] == '>') {
          s1[i][0] = '<';
          if (s1[i][1] == '=')
            s1[i][1] = '\0';
          else
            s1[i][1] = '=';
        }
      }
    }
    if (s1[i][0] == '<' && s1[i][1] == '=') {
      l[i] = l[i - 1];
      r[i] = x[i];
    }
    if (s1[i][0] == '<' && s1[i][1] != '=') {
      l[i] = l[i - 1];
      r[i] = x[i] - 1;
    }
    if (s1[i][0] == '>' && s1[i][1] == '=') {
      r[i] = r[i - 1];
      l[i] = x[i];
    }
    if (s1[i][0] == '>' && s1[i][1] != '=') {
      r[i] = r[i - 1];
      l[i] = x[i] + 1;
    }
    if (l[i] > r[i]) flag = 0;
    lx = max(lx, l[i]);
    ly = min(ly, r[i]);
  }
  if (lx > ly) flag = 0;
  if (flag) {
    printf("%I64d\n", lx);
  } else
    printf("Impossible\n");
  return 0;
}
