#include <bits/stdc++.h>
using namespace std;
inline void read(int &x) {
  char c = getchar();
  int p = 1;
  x = 0;
  while (!isdigit(c)) {
    if (c == '-') p = -1;
    c = getchar();
  }
  while (isdigit(c)) {
    x = (x << 1) + (x << 3) + (c ^ '0');
    c = getchar();
  }
  x *= p;
}
map<char, int> ma;
vector<char> vec;
char str[100005];
int main() {
  scanf("%s", str + 1);
  int len = strlen(str + 1);
  for (register int i = 1; i <= len; ++i) {
    ma[str[i]]++;
    if (ma[str[i]] == 1) vec.push_back(str[i]);
  }
  int Ans = vec.size();
  if (Ans == 3) {
    bool flag = 0;
    for (register int i = 0; i < Ans; ++i) {
      if (ma[vec[i]] >= 2) {
        flag = 1;
        break;
      }
    }
    if (flag)
      cout << "Yes" << endl;
    else
      cout << "No" << endl;
  } else if (Ans == 4) {
    cout << "Yes" << endl;
  } else if (Ans == 2) {
    if (ma[vec[0]] >= 2 && ma[vec[1]] >= 2)
      cout << "Yes" << endl;
    else
      cout << "No" << endl;
  } else
    cout << "No" << endl;
  return 0;
}
