import std.stdio,
  std.array,
  std.conv,
  std.string,
  std.algorithm;

bool check(string s)
{
  int cnt = 0;
  bool exist = false;
  if (s[$-1] != 'R') {
    return false;
  }
  foreach(char c; s) {
    if (c == 'G') {
      cnt++;
    }
    else if (c == 'R') {
      cnt--;
      exist = true;
    }
    if (cnt < 0) {
      return false;
    }
  }
  return exist;
}

void main()
{
  int n = readln.chomp.to!int;
  foreach (i; 0..n) {
    bool possible = check(readln.chomp);
    if (possible) {
      writeln("possible");
    }
    else {
      writeln("impossible");
    }
  }
}