Innokentiy likes tea very much and today he wants to drink exactly n cups of tea. He would be happy to drink more but he had exactly n tea bags, a of them are green and b are black.

Innokentiy doesn't like to drink the same tea (green or black) more than k times in a row. Your task is to determine the order of brewing tea bags so that Innokentiy will be able to drink n cups of tea, without drinking the same tea more than k times in a row, or to inform that it is impossible. Each tea bag has to be used exactly once.

Input

The first line contains four integers n, k, a and b (1 ≤ k ≤ n ≤ 105, 0 ≤ a, b ≤ n) — the number of cups of tea Innokentiy wants to drink, the maximum number of cups of same tea he can drink in a row, the number of tea bags of green and black tea. It is guaranteed that a + b = n.

Output

If it is impossible to drink n cups of tea, print "NO" (without quotes).

Otherwise, print the string of the length n, which consists of characters 'G' and 'B'. If some character equals 'G', then the corresponding cup of tea should be green. If some character equals 'B', then the corresponding cup of tea should be black.

If there are multiple answers, print any of them.

Examples

Input

5 1 3 2


Output

GBGBG


Input

7 2 2 5


Output

BBGBGBB

Input

4 3 4 0


Output

NO
#include <bits/stdc++.h>
using namespace std;
struct outFloat {
  int precision;
  long double value;
  outFloat(long double v, int p) : precision(p), value(v) {}
};
template <typename T>
struct debugInfo {
  string name;
  T val;
  debugInfo(const char* n, T v) : name(n), val(v){};
};
template <typename T>
debugInfo<T> makeDebugInfo(const char* n, T v) {
  return debugInfo<T>(n, v);
}
const int inf = 123456789;
const long long llInf = 123456789012345678LL;
const long double pi = 3.14159265358979323846;
const int maxN = 2000000;
int init() {
  ios_base::sync_with_stdio(0);
  srand(time(NULL));
  return 0;
}
int initializer = init();
template <typename T1, typename T2>
istream& operator>>(istream& is, pair<T1, T2>& p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T>
istream& operator>>(istream& is, vector<T>& p) {
  for (int i = 0; i < p.size(); i++) is >> p[i];
  return is;
}
class inputer {
 private:
  istream* istr;

 public:
  inputer(istream& is) : istr(&is) {}
  template <typename T>
  void get(T& n) {
    (*istr) >> n;
  }
  template <typename T, typename... Args>
  void get(T& n, Args&... args) {
    get(n);
    get(args...);
  }
  template <typename... Args>
  void getLn(Args&... args) {
    get(args...);
    getLn();
  }
  template <typename T>
  operator T() {
    T n;
    get(n);
    return n;
  }
  void getLn() {
    string s;
    getline(cin, s);
  }
  template <typename T>
  void getv(vector<T>& v, int size) {
    v.resize(size);
    (*istr) >> v;
  }
};
string delim = " ";
template <typename T1, typename T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& p) {
  os << p.first << delim << p.second;
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& p) {
  for (int i = 0; i < p.size(); i++) {
    if (i != 0) os << delim;
    os << p[i];
  }
  return os;
}
ostream& operator<<(ostream& os, const outFloat& of) {
  os << setprecision(of.precision) << of.value;
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, const debugInfo<T>& dbg) {
  os << "\"" << dbg.name << "\" = \"" << dbg.val << "\""
     << "\n";
}
class outputer {
 private:
  ostream* ostr;

 public:
  outputer(ostream& os) : ostr(&os) {}
  template <typename T>
  void put(const T& n) {
    (*ostr) << n;
  }
  template <typename T, typename... Args>
  void put(const T& n, const Args&... args) {
    put(n);
    put(args...);
  }
  template <typename... Args>
  void putLn(const Args&... args) {
    put(args...);
    putLn();
  }
  template <typename T>
  outputer& operator=(const T& n) {
    putLn(n);
    return *this;
  }
  void putLn() { (*ostr) << "\n"; }
  template <typename T>
  void putv(vector<T> v, int size, string delim) {
    for (int i = 0; i < size; i++) {
      if (i != 0) (*ostr) << delim;
      (*ostr) << v[i];
    }
  }
};
inputer in(cin);
outputer out(cout);
char getChar() {
  char c = 0;
  while (c <= ' ') cin >> c;
  return c;
}
bool willItBeAC() {
  return true;
  ;
}
int getMyRating() { return 2048; }
bool prime(long long n) {
  for (long long i = 2; i * i <= n; i++)
    if (n % i == 0) return false;
  return true;
}
vector<long long> divs(long long n) {
  vector<long long> v;
  long long i = 2;
  while (i * i <= n)
    if (n % i == 0) {
      n /= i;
      v.push_back(i);
    } else
      i++;
  v.push_back(n);
  return v;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long extGcd(long long a, long long b, long long& x, long long& y) {
  if (a == 0) {
    x = 0;
    y = 1;
    return b;
  }
  long long x1, y1, d = extGcd(b % a, a, x1, y1);
  x = y1 - (b / a) * x1;
  y = x1;
  return d;
}
template <typename T>
class fenwick {
 private:
  vector<T> t;
  int n;

 public:
  fenwick(int nn) { init(nn); }
  void init(int nn) {
    n = nn;
    t.assign(n, 0);
  }
  T sum(int r) {
    T result = 0;
    for (; r >= 0; r = (r & (r + 1)) - 1) result += t[r];
    return result;
  }
  void inc(int i, T delta) {
    for (; i < n; i = (i | (i + 1))) t[i] += delta;
  }
  T sum(int l, int r) { return sum(r) - sum(l - 1); }
  T get(int i) { return sum(i, i); }
  void put(int i, T v) { inc(i, v - sum(i, i)); }
  int size() { return n; }
};
int main() {
  int n = in, k = in, a = in, b = in;
  char qa = 'G', qb = 'B';
  if (a < b) {
    swap(a, b);
    swap(qa, qb);
  }
  int grSz = n / (b + 1);
  if (grSz > k) {
    out = "NO";
    return 0;
  }
  for (int i = 0; i <= b; i++) {
    if (i != 0) out.put(qb);
    int curG = grSz;
    if (i > (n % (b + 1))) curG--;
    for (int i = 0; i < curG; i++) out.put(qa);
  }
  out.putLn();
  return 0;
}
