#include<iostream>
#include<iomanip>
#include<math.h>
#include<vector>
#include<algorithm>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<string>
#include<bitset>
#include<random>
#define INF 1000000000ll
#define MOD 1000000007ll
#define EPS 1e-10
#define REP(i,m) for(long long i=0; i<m; i++)
#define FOR(i,n,m) for(long long i=n; i<m; i++)
#define DUMP(a) for(long long dump=0; dump<(ll)a.size(); dump++) { cout<<a[dump]; if(dump!=(ll)a.size()-1) cout<<" "; else cout<<endl; }
#define ALL(v) v.begin(),v.end()
#define pb push_back
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
typedef long double ld;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll t;
	cin>>t;
	REP(roop,t) {
		ll gc=0;
		string s;
		cin>>s;
		bool d=true;
		REP(i,(ll)s.size()) {
			if(s[i]=='G') gc++;
			if(s[i]=='R') {
				if(gc>0) gc--;
				else d=false;
			}
		}
		if(d&&gc==0&&s[(ll)s.size()-1]!='W') cout<<"possible"<<endl;
		else cout<<"impossible"<<endl;
	}
}