import std.algorithm, std.array, std.container, std.range;
import std.numeric, std.math, std.bigint, std.bitmanip, std.random;
import std.string, std.conv, std.stdio, std.typecons;

void main()
{
  auto t = readln.chomp.to!int;

  foreach (_; 0..t) {
    auto s = readln.chomp;

    writeln(calc(s) ? "possible" : "impossible");
  }
}

bool calc(string s)
{
  auto a = 0, b = 0, c = 0, d = 0;

  foreach_reverse (t; s){
    switch (t) {
    case 'R':
      a += 1;
      b += 1;
      break;
    case 'G':
      c += 1;
      b -= 1;
      if (b < 0) return false;
      break;
    case 'W':
      d += 1;
      if (c < 0) return false;
      break;
    default:
    }
  }

  return a <= d;
}