#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstring>
#include <algorithm>
#include <limits.h>
#include <cmath>
#include <cstdio>
#include <vector>
#include <set>
#include <string>
#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
using namespace std;

typedef long long ll;
typedef unsigned long long ull;

bool possible(char S[]) {
  int i;
  int n = strlen(S);
  int Gcnt = 0,Rcnt = 0,Wcnt = 0;
  bool possible = true;
  // R より Gの方が先に来てないか判定
  rep(i,n) {
    if(S[i] == 'G') Gcnt++;
    else if(S[i] == 'R') Rcnt++;
    else Wcnt++;
    if(Gcnt < Rcnt) {
      possible = false;
      break;
    }
  }
  if(Rcnt != Gcnt) possible = false;
  if(S[n-1] != 'R') possible = false;
  for(i=n-2;i>-1;i--) {
    if(S[i] == 'W') possible = false;
    else if(S[i] == 'B') break;
  }
  // 3本以上走ってるか
  return possible;
}
int main(void)
{
  int i,j,k,l;
  int T;
  char S[1005] = "";
  cin >> T;
  while(cin >> S) {
    if(possible(S)) puts("possible");
    else puts("impossible");
  }
  return 0;
}