#include <iostream>
#include <cstdio>
using namespace std;
int main() {
int n, x, l=-2*1e9, r=2*1e9;
char s1[5], s2[5];
scanf("%d", &n);
while(n--) {
scanf("%s%d%s", s1, &x, s2);
if(s1[0]=='>' && s1[1]=='=' && s2[0]=='Y' && x>l) l=x;
else if(s1[0]=='>' && s1[1]!='=' && s2[0]=='Y' && x+1>l) l=x+1;
else if(s1[0]=='>' && s1[1]=='=' && s2[0]=='N' && x-1<r) r=x-1;
else if(s1[0]=='>' && s1[1]!='=' && s2[0]=='N' && x<r) r=x;
else if(s1[0]=='<' && s1[1]=='=' && s2[0]=='Y' && x<r) r=x;
else if(s1[0]=='<' && s1[1]!='=' && s2[0]=='Y' && x-1<r) r=x-1;
else if(s1[0]=='<' && s1[1]=='=' && s2[0]=='N' && x+1>l) l=x+1;
else if(s1[0]=='<' && s1[1]!='=' && s2[0]=='N' && x>l) l=x;
}
if(l<=r) printf("%d", l);
else printf("Impossible");
return 0;
}
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