#include <bits/stdc++.h>
#define WHITE 0
#define GREEN 1
#define RED 2

using namespace std;

int T;
string S;

bool pos(){
    
    int color[3] = {0};
    
    int i;
    for(i = S.size() - 1; i >= 0; --i){
        if(S[i] == 'G') ++color[GREEN];
        if(S[i] == 'R') ++color[RED];
        if(S[i] == 'W') ++color[WHITE];
        if((color[WHITE] != 0 && color[GREEN] == 0) || (color[WHITE] != 0 && color[RED] == 0)) return false;
        if(color[GREEN] > color[RED]) return false;
    }
    if(color[GREEN] != color[RED]) return false;
    if(color[WHITE] < color[RED]) return false;
    
    return true;
}

int main(void){
    
    cin >> T;
    
    int i;
    for(i = 0; i < T; ++i){
        cin >> S;
        if(pos()) cout << "possible" << endl;
        else cout << "impossible" << endl;
    }
    
    return 0;
}