//No.154 市バス

import java.util.*;
import java.io.*;
import static java.util.Arrays.*;
import static java.lang.Math.*;

public class No154 {

    static final InputStream in = System.in;
    static final PrintWriter out = new PrintWriter(System.out,false);

    static void solve(){
        int t = nextInt();
        while (t-- > 0) {
            char[] cs = next().toCharArray();
            out.println((check(cs) && check2(cs)) ? "possible" : "impossible");
        }
    }

    static boolean check(char[] cs) {
        int n = cs.length;
        int[] wgr = new int[3];
        for (int i=0; i<n; i++) {
            wgr[cs[i]=='W'?0:(cs[i]=='G'?1:2)]++;
        }
        if (wgr[1] != wgr[2] || wgr[0] < wgr[1]) return false;
        return true;
    }

    static boolean check2(char[] cs) {
        int n = cs.length;
        boolean[] wgr = new boolean[3];
        int cnt = 0;
        for (int i=n-1; i>=0; i--) {
            if (cs[i] == 'X') {cnt++; continue;}
            if (cs[i] == 'R') {
                if (!wgr[2]) {
                    wgr[2] = true;
                    cs[i] = 'X';
                }
            }else {
                if (!wgr[2]) return false;
                if (cs[i] == 'G') {
                    if (!wgr[1]) {
                       wgr[1] = true;
                        cs[i] = 'X'; 
                    }else if (wgr[0]) {
                        break;
                    }
                }else {
                    if (!wgr[1] || !wgr[1]) return false;
                    wgr[0] = true;
                    cs[i] = 'X';
                }
            }
        }
        if (cnt == n) return true;
        if (!wgr[0] || !wgr[1] || !wgr[2]) return false;
        return check2(cs);
    }

    public static void main(String[] args) throws Exception {
        long start = System.currentTimeMillis();

        solve();
        out.flush();

        long end = System.currentTimeMillis();
        //trace(end-start + "ms");
        in.close();
    }

    static void trace(Object... o) { System.out.println(deepToString(o));}

    static final byte[] buf = new byte[1024];
    static int ptr = 0;
    static int buflen = 0;

    static boolean hasNextByte() {
        if (ptr < buflen)
            return true;
        ptr = 0;
        try{
            buflen = in.read(buf);
        }catch (IOException e) {e.printStackTrace();}
        if (buflen <= 0)
            return false;
        return true;
    }

    static int readByte() { if (hasNextByte()) return buf[ptr++]; else return -1;}

    static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}

    static void skip() { while(hasNextByte() && !isPrintableChar(buf[ptr])) ptr++;}

    static boolean hasNext() {skip(); return hasNextByte();}

    static String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    static long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        boolean minus = false;
        long num = readByte();

        if(num == '-'){
            num = 0;
            minus = true;
        }else if (num < '0' || '9' < num){
            throw new NumberFormatException();
        }else{
            num -= '0';
        }
        
        while(true){
            int b = readByte();
            if('0' <= b && b <= '9')
                num = num * 10 + (b - '0');
            else if(b == -1 || !isPrintableChar(b))
                return minus ? -num : num;
            else
                throw new NoSuchElementException();
        }
    }

    static int nextInt() {
        long num = nextLong();
        if (num < Integer.MIN_VALUE || Integer.MAX_VALUE < num)
            throw new NumberFormatException();
        return (int)num;
    }

    static double nextDouble() {
        return Double.parseDouble(next());
    }

    static char nextChar() {
        if (!hasNext()) throw new NoSuchElementException();
        return (char)readByte();
    }

    static String nextLine() {
        while (hasNextByte() && (buf[ptr] == '\n' || buf[ptr] == '\r')) ptr++;
        if (!hasNextByte()) throw new NoSuchElementException();

        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (b != '\n' && b != '\r') {
            sb.appendCodePoint(b);
            b = readByte();
        }

        return sb.toString();
    }

    static int[] nextArrayInt(int n) {
        int[] a = new int[n];
        for (int i=0; i<n; i++) a[i] = nextInt();
        return a;
    }
}