// [4/13/2014 Sjm]
/*
关键： 寻找 左右区间，判断此区间是否合理。
*/
1 #include <iostream>
2 #include <cstdio>
3 #include <cstdlib>
4 #include <string>
5 #include <algorithm>
6 using namespace std;
7 const int MAX = 2000000000, MIN = -2000000000;
8
9 int main()
10 {
11 //freopen("input.txt", "r", stdin);
12 //freopen("output.txt", "w", stdout);
13 int n, lef = MIN, rig = MAX, temp;
14 string str;
15 char c;
16 scanf("%d", &n);
17 while (n--)
18 {
19 cin >> str;
20 scanf("%d %c", &temp, &c);
21 if ('N' == c) {
22 if (">" == str) str = "<=";
23 else {
24 if ("<" == str) str = ">=";
25 else {
26 if ("<=" == str) str = ">";
27 else str = "<";
28 }
29 }
30 }
31 if (">" == str) lef = max(lef, temp + 1);
32 else {
33 if ("<" == str) rig = min(rig, temp - 1);
34 else {
35 if (">=" == str) lef = max(lef, temp);
36 else rig = min(rig, temp);
37 }
38 }
39 }
40 if (lef > rig) printf("Impossible\n");
41 else printf("%d\n", lef);
42 return 0;
43 }
