#include <bits/stdc++.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}

using namespace std;

const int dx[8]={1,0,-1,0,1,-1,-1,1};
const int dy[8]={0,1,0,-1,1,1,-1,-1};


int main(void){
	int t;
	cin >> t;
	rep(loop,t){
		string s;
		cin >> s;
		int n=s.size();

		bool ok=true;
		
		int white=0,green=0,red=0,bus=0;
		rep(i,n) if(s[i]=='R') bus++;

		rep(i,n){
			if(bus==0 && s[i]!='R') ok=false;
			if(s[i]=='W') white++;
			if(s[i]=='G') green++,bus--;
			if(s[i]=='R') red++;

			if(white<green) ok=false;
			if(green<red) ok=false;
		}
		
		//if(s[n-1]!='R') ok=false;
		if(green != red) ok=false;
		if(red==0) ok=false;

		if(ok)
			puts("possible");
		else
			puts("impossible");
	}
	return 0;
}