import std.algorithm, std.container, std.conv, std.math, std.range, std.typecons, std.stdio, std.string;

auto rdsp(){return readln.splitter;}
void pick(R,T)(ref R r,ref T t){t=r.front.to!T;r.popFront;}
void readV(T...)(ref T t){auto r=rdsp;foreach(ref v;t)pick(r,v);}

void main()
{
  int n; readV(n);

  auto calc(string s)
  {
    auto r = 0, g = 0, w = 0;
    foreach_reverse (c; s)
      switch (c) {
      case 'R':
        ++r;
        break;
      case 'G':
        if (g == r) return false;
        ++g;
        break;
      case 'W':
        if (g == 0) return false;
        if (w < g) ++w;
        break;
      default:
        assert(0);
      }

    return r == g && g == w;
  }

  foreach (_; 0..n) {
    string s; readV(s);
    writeln(calc(s) ? "possible" : "impossible");
  }
}