import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		int T = sc.nextInt();
		
		for(int i=0; i<T; i++) {
		
			char[] S = sc.next().toCharArray();
						
			//一番右はR
			if(S[S.length-1] != 'R') {
				System.out.println("impossible");
				continue;
			}
			
			//RとＧの個数は同じ
			int rNum = getCharCount(S, 'R');
			int gNum = getCharCount(S, 'G');
			if(rNum>0 && gNum>0 && (rNum==gNum)) {
				
			} else {
				System.out.println("impossible");
				continue;
			}
			
			int r, g, w;
			//一番右のＧより右にＷがあってはだめ
			g = getCharIndex(S, S.length, 'G');
			w = getCharIndex(S, S.length, 'W');
			if(g>0 && w>0 && (w<g)) {
				
			} else {
				System.out.println("impossible");
				continue;
			}
			
			for(int j=0; j<rNum; j++) {
			
				r = getCharIndex(S, S.length, 'R');
				g = getCharIndex(S, r,        'G');
				w = getCharIndex(S, g,        'W');
								
				if(r<0 || g<0 || w<0) {
					break;
				}
				
				if( (r > g && r > w) && (w < g && w < r) ) {
					S[r] = S[g] = S[w] = ' ';
				} else {
					break;
				}
			}
			
			rNum = getCharCount(S, 'R');
			if(rNum == 0) {
				System.out.println("possible");
			} else {
				System.out.println("impossible");
			}
		}
	}
	
	static int getCharIndex(char[] list, int edge, char c) {
		for(int i=edge-1; i>=0; i--) {			
			if(list[i] == c) return i;
		}
		return -1;
	}
	
	static int getCharCount(char[] list, char c) {
		int ret = 0;
		for(int i=0; i<list.length; i++) {
			if(list[i] == c) ret++;
		}
		return ret;
	}
}