#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<long double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-8;
const ll mod=1e9+7;
const int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

int q,n;
string s;

int main(){
	cin>>q;
	for(int i=0;i<q;i++){
		cin>>s;
		n=s.size();
		int B=1,x=0,y=0,z=0;
		vi a(n);
		for(int i=0;i<n;i++){
			if(s[i]=='G') a[i]=1,y++;
			else if(s[i]=='R') a[i]=2,z++;
			else x++;
		}
		if(y!=z||x<y||y==0) B=0;
		vi b;
		for(auto i:a){
			if(i) b.push_back(i);
			else if(z) b.push_back(0),z--;
		}
		x=0,y=0;
		for(auto i:b){
			if(i==0) x++;
			if(i==1) x--,y++;
			if(i==2) y--;
			if(x<0||y<0) B=0;
		}
		for(int i=n-1;i>=0;i--) if(a[i]==1){
			for(int j=i;j<n;j++) if(!a[j]) B=0;
			break;
		}
		cout<<(B?"possible":"impossible")<<endl;
	}
}