A. Guess a number!

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

A TV show called "Guess a number!" is gathering popularity. The whole Berland, the old and the young, are watching the show.

The rules are simple. The host thinks of an integer y and the participants guess it by asking questions to the host. There are four types of acceptable questions:

• Is it true that y is strictly larger than number x?
• Is it true that y is strictly smaller than number x?
• Is it true that y is larger than or equal to number x?
• Is it true that y is smaller than or equal to number x?

On each question the host answers truthfully, "yes" or "no".

Given the sequence of questions and answers, find any integer value of y that meets the criteria of all answers. If there isn't such value, print "Impossible".

Input

The first line of the input contains a single integer n (1 ≤ n ≤ 10000) — the number of questions (and answers). Next n lines each contain one question and one answer to it. The format of each line is like that: "sign x answer", where the sign is:

• ">" (for the first type queries),
• "<" (for the second type queries),
• ">=" (for the third type queries),
• "<=" (for the fourth type queries).

All values of x are integer and meet the inequation  - 109 ≤ x ≤ 109. The answer is an English letter "Y" (for "yes") or "N" (for "no").

Consequtive elements in lines are separated by a single space.

Output

Print any of such integers y, that the answers to all the queries are correct. The printed number y must meet the inequation  - 2·109 ≤ y ≤ 2·109. If there are many answers, print any of them. If such value doesn't exist, print word "Impossible" (without the quotes).

Sample test(s)

input

4>= 1 Y< 3 N<= -3 N> 55 N

output

17

input

2> 100 Y< -100 Y

output

Impossible

解题说明：此题就是找好两个区间即可，通过输入条件判断区间的前后端。

#include<iostream>#include<cstdio>#include<cmath>#include<cstdlib>#include <algorithm>#include<cstring>#include<string>using namespace std;int main(){int begin,end,t,i,temp;int bb, ee;string op;string flag;begin = -2000000000;end = 2000000000;cin >> t;for (i = 0; i < t; i++){cin >> op >> temp >> flag;if (flag=="Y"){if (op == ">="){bb = temp;if (begin < bb){begin = bb;}}else if (op == "<="){ee = temp;if (end>ee){end = ee;}}else if (op == ">"){bb = temp + 1;if (begin < bb){begin = bb;}}else{ee = temp - 1;if (end>ee){end = ee;}}}else{if (op == ">="){ee = temp-1;if (end>ee){end = ee;}}else if (op == "<="){bb = temp+1;if (begin < bb){begin = bb;}}else if (op == ">"){ee = temp ;if (end>ee){end = ee;}}else{bb = temp ;if (begin < bb){begin = bb;}}}}if (begin > end){cout << "Impossible" << endl;}else{cout << begin  << endl;}return 0;}