Guess a number! CodeForces

          

 

     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).

Example

Input

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

Output

17

Input

2
> 100 Y
< -100 Y

Output

Impossible

根据输入的数据不断更新区间的左右端点，注意更新是有效的！！！

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<string>
using namespace std;

typedef long long ll;
static const int INF=2e9+5;

int main()
{   int n;
    while(~scanf("%d",&n)){
        string s,s1,a,b,c,d,e;
        a=">=",b=">",c="<=",d="<",e="Y";
        ll x,l=-INF,r=INF;     
        for(int i=1;i<=n;i++){
            cin>>s>>x>>s1;
            if(s==a){
                if(s1==e) l=max(l,x);
                else r=min(r,x-1); 
            }
            if(s==b){
                if(s1==e) l=max(l,x+1);
                else r=min(r,x); 
            }
            if(s==c){
                if(s1==e) r=min(r,x);
                else l=max(l,x+1);
            }
            if(s==d){
                if(s1==e) r=min(r,x-1);
                else l=max(l,x);
            }
        }
        if(l>r) printf("Impossible
");
        else{
             if((l+r)%2==0) printf("%lld
",(l+r)/2);
             else printf("%lld
",(l+r+1)/2);
        }
    }
}