#include "bits/stdc++.h"
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a) for(int i=0;i<a;i++)
#define GET_ARRAY_SIZE(a) (sizeof(a)/sizeof(a[0]))
typedef long long ll;
typedef pair<int, int> PI;
typedef pair<int, PI> V;
typedef vector<int> VE;
const ll mod = 1000000007;

int main(){
  int n;
  cin>>n;
  REP(i,n){
    string s;
    cin>>s;
    int w=0;
    int g=0;
    int r=0;
    bool flag=1;
    int set=0;
    for(int j=s.size()-1;j>=0;j--){
      if(s[j]=='G'){g++;}
      else if(s[j]=='R'){r++;}
      else if(s[j]=='W'){
        w++;
        set=min(set+1,g);
      }
      if(w!=0&&g==0)flag=0;
      if(w!=0&&r==0)flag=0;
      if(r<g)flag=0;
    }
    if(r!=g||w<g||set!=g)flag=0;
    string ans=flag?"possible":"impossible";
    print(ans);
  }
}