#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-9;
const int INFMEM = 63;
const int INF = 1061109567;
const long long LINF = 4557430888798830399LL;
const double DINF = numeric_limits<double>::infinity();
const long long MOD = 1000000007;
const int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
const int dy[8] = {0, 1, 0, -1, 1, -1, 1, -1};
const double PI = 3.141592653589793;
inline void fastin(int &input_number) {
  input_number = 0;
  int ch = getchar_unlocked();
  int sign = 1;
  while (ch < '0' || ch > '9') {
    if (ch == '-') sign = -1;
    ch = getchar_unlocked();
  }
  while (ch >= '0' && ch <= '9') {
    input_number = (input_number << 3) + (input_number << 1) + ch - '0';
    ch = getchar_unlocked();
  }
  input_number *= sign;
}
inline void fastll(long long &input_number) {
  input_number = 0;
  int ch = getchar_unlocked();
  int sign = 1;
  while (ch < '0' || ch > '9') {
    if (ch == '-') sign = -1;
    ch = getchar_unlocked();
  }
  while (ch >= '0' && ch <= '9') {
    input_number = (input_number << 3) + (input_number << 1) + ch - '0';
    ch = getchar_unlocked();
  }
  input_number *= sign;
}
inline void open(string a) {
  freopen((a + ".in").c_str(), "r", stdin);
  freopen((a + ".out").c_str(), "w", stdout);
}
inline void fastios() { ios_base::sync_with_stdio(0); }
inline void fasterios() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
string s;
map<char, long long> isi;
int main() {
  map<char, long long>::iterator it;
  cin >> s;
  for (int i = 0; i < s.length(); i++) isi[s[i]]++;
  if (isi.size() >= 5)
    cout << "No" << '\n';
  else if (isi.size() == 4)
    cout << "Yes" << '\n';
  else if (isi.size() == 1)
    cout << "No" << '\n';
  else if (isi.size() == 2) {
    for (it = isi.begin(); it != isi.end(); it++)
      if (it->second == 1) {
        cout << "No" << '\n';
        return 0;
      }
    cout << "Yes" << '\n';
  } else if (isi.size() == 3 && s.length() == 3)
    cout << "No" << '\n';
  else
    cout << "Yes" << '\n';
  return 0;
}
