#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
#include <tuple>
#include <utility>
using namespace std;

namespace {
  using Integer = long long; //__int128;
  template<class T, class S> istream& operator >> (istream& is, pair<T,S>& p){return is >> p.first >> p.second;}
  template<class T> istream& operator >> (istream& is, vector<T>& vec){for(T& val: vec) is >> val; return is;}
  template<class T> istream& operator ,  (istream& is, T& val){ return is >> val;}
  template<class T, class S> ostream& operator << (ostream& os, const pair<T,S>& p){return os << p.first << " " << p.second;}
  template<class T> ostream& operator << (ostream& os, const vector<T>& vec){for(size_t i=0; i<vec.size(); i++) os << vec[i] << (i==vec.size()-1?"":" "); return os;}
  template<class T> ostream& operator ,  (ostream& os, const T& val){ return os << " " << val;}

  template<class H> void print(const H& head){ cout << head; }
  template<class H, class ... T> void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); }
  template<class ... T> void println(const T& ... values){ print(values...); cout << endl; }

  template<class H> void eprint(const H& head){ cerr << head; }
  template<class H, class ... T> void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); }
  template<class ... T> void eprintln(const T& ... values){ eprint(values...); cerr << endl; }

  class range{ Integer start_, end_, step_; public: struct range_iterator{ Integer val, step_; range_iterator(Integer v, Integer step) : val(v), step_(step) {} Integer operator * (){return val;} void operator ++ (){val += step_;} bool operator != (range_iterator& x){return step_ > 0 ? val < x.val : val > x.val;} }; range(Integer len) : start_(0), end_(len), step_(1) {} range(Integer start, Integer end) : start_(start), end_(end), step_(1) {} range(Integer start, Integer end, Integer step) : start_(start), end_(end), step_(step) {} range_iterator begin(){ return range_iterator(start_, step_); } range_iterator   end(){ return range_iterator(  end_, step_); } };

  inline string operator "" _s (const char* str, size_t size){ return move(string(str)); }
  constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);}
  constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);}
  constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); }

  inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed

  mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());

  template<class T> string join(const vector<T>& v, const string& sep){ stringstream ss; for(size_t i=0; i<v.size(); i++){ if(i>0) ss << sep; ss << v[i]; } return ss.str(); }

  inline string operator * (string s, int k){ string ret; while(k){ if(k&1) ret += s; s += s; k >>= 1; } return ret; }
}
constexpr long long mod = 9_ten + 7;
int h,w,d;

bool check(vector<string>& a){
  for(int i=0; i<h; i++) for(int j=0; j<w; j++){
    for(int k=-d; k<=d; k++){
      int y = i+k;
      int x = j+(d-abs(k));
      if( y>=0 && y<h && x>=0 && x<w){
        if( a[i][j] == a[y][x] ) return false;
      }
      x = j-(d-abs(k));
      if( y>=0 && y<h && x>=0 && x<w){
        if( a[i][j] == a[y][x] ) return false;
      }
    }
  }
  return true;
}

int main(){
  cin >> h,w,d;

  string color = "RGBY";

  // vector<string> a(h);
  // cin >> a;
  // println(check(a) ? 1 : 0);

  if(d%2){
    vector<string> a(h, string(w, '.'));
    for(int i=0; i<h && i<w; i++){
      a[i][i] = color[0];
    }
    for(int i=0; i<h; i++){
      for(int j=0; j<w; j++){
        a[i][j] = color[(i+j)%2];
      }
    }
    println(join(a,"\n"));

    eprintln(check(a) ? "OK" : "BAD");
    return 0;
  }else{
    w += 2;
    vector<string> a(h, string(w, ' '));

    for(int y=1000, x=-1000, k=0; y>=-1000; y--,x++, k++){
      int c = ((k/(d/2))%2)<<1;
      int yy=y;
      int xx=x;
      int t=0;
      while(yy<h && xx<w){
        if(xx>=0 && xx<w && yy>=0 && yy<h){
          a[yy][xx] = color[c|((t/(d/2))&1)];
        }
        yy++;
        xx++;
        t++;
      }
    }
    for(int i=0; i<h; i++){
      for(int j=i%2; j<w; j+=2){
        a[i][j+1] = a[i][j];
      }
    }

    w -= 2;
    for(int i=0; i<h; i++){
      a[i] = a[i].substr(1,w);
    }
    println(join(a,"\n"));
    eprintln(check(a) ? "OK" : "BAD");
  }

  return 0;
}


Measured memory_bytes: 1164