#include <string>
#include <iostream>
using namespace std;

int main() {
    string s;
    cin >> s;
    while ( cin >> s ) {
        int w = 0, g = 0, r = 0, l = 0;
        for ( char i : s ) { l += i == 'R' ? 1 : 0; }
        int f = s[0] != 'W' ? 1 : 0;
        for ( char i : s ) {
            if ( i == 'W' ) {
                w += 1;
                if ( l == 0 ) {
                    f = 1;
                }
            }
            if ( i == 'G' ) {
                if ( l > 0 && w > 0 ) {
                    w -= 1; l -= 1; g += 1;
                } else {
                    f = 1;
                }
            }
            if ( i == 'R' ) {
                if ( g > 0 ) {
                    g -= 1; r += 1;
                } else {
                    f = 1;
                }
            }
            if ( f ) { break; }
        }
        string o = !f && g == 0 ? "possible" : "impossible";
        cout << o << endl;
    }
    return 0;
}