#include <bits/stdc++.h>
//#include<boost/multiprecision/cpp_int.hpp>
//#include<boost/multiprecision/cpp_dec_float.hpp>
//#include <atcoder/all>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a; i >-1; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a; i > b; --i)
#define repl(i, a) for (ll i = (ll)0; i < (ll)a; ++i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
#define fi first
#define se second
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll mod_998244353 = 998244353;
constexpr ll INF = 1LL << 60;

// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

//using lll=boost::multiprecision::cpp_int;
//using Double=boost::multiprecision::number<boost::multiprecision::cpp_dec_float<128>>;//仮数部が1024桁
template <class T>
inline bool chmin(T &a, T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}

ll mypow(ll x, ll n, const ll &p = -1)
{ //x^nをmodで割った余り

	if (p != -1)
	{
		x =(x%p+p)%p;
	}
	ll ret = 1;
	while (n > 0)
	{
		if (n & 1)
		{
			if (p != -1)
				ret = (ret * x) % p;
			else
				ret *= x;
		}
		if (p != -1)
			x = (x * x) % p;
		else
			x *= x;
		n >>= 1;
	}
	return ret;
}

using namespace std;
//using namespace atcoder;


void ng(){
	cout<<"impossible\n";
}

void solve()
{	
	int t;
	cin>>t;
	while(t--){
		string s;
		cin>>s;
		int n=s.size();
		int x=0;
		bool no=false;
		rep(i,n){
			if(s[i]=='G'){
				++x;
			}else if(s[i]=='R'){
				if(x<=0)no=true;
				else --x;
			}
		}
		if(x!=0)no=true;
		x=0;
		rep(i,n){
			if(s[i]=='W')++x;
			else if(s[i]=='G'){
				if(x<=0)no=true;
				else --x;
			}
		}
		x=0;
		rep(i,n){
			if(s[i]=='W')++x;
			else if(s[i]=='G'){
				if(x<=0)no=true;
				else --x;
			}
		}
		int g=0,r=0;
		RREP(i,n-1,-1){
			if(s[i]=='G')++g;
			else if(s[i]=='R')++r;
			else break;
		}
		if(g==0||r==0)no=true;
		if(no)ng();
		else{
			cout<<"possible\n";
		}
	}
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}