#include <bits/stdc++.h>
using namespace std;
int n, tt, mn, mx, ans = 0;
int arr[100005];
string s;
void init() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
}
int cnt = 0;
map<char, int> ck1;
int main() {
  init();
  cin >> s;
  for (int i = 0; i < s.length(); i++) {
    if (ck1[s[i]] == 0) {
      cnt++;
      ck1[s[i]] = 1;
    }
  }
  if (cnt == 1 || cnt > 4) {
    cout << "No";
  } else if (cnt == 4)
    cout << "Yes";
  else {
    int i;
    int cc[4], ccc = 0;
    memset(cc, 0, sizeof cc);
    map<char, int> ck2, pos;
    for (int i = 0; i < s.length(); i++) {
      if (ck2[s[i]] == 0) {
        pos[s[i]] = ccc++;
        ck2[s[i]] = 1;
      }
      cc[pos[s[i]]]++;
    }
    if (cnt == 2) {
      if (cc[0] > 1 && cc[1] > 1)
        cout << "Yes";
      else
        cout << "No";
    } else if (cnt == 3) {
      sort(cc, cc + 3);
      if (cc[2] > 1)
        cout << "Yes";
      else
        cout << "No";
    }
  }
}
