#include <bits/stdc++.h>
using namespace std;
ifstream fin("date.in");
ofstream fout("date.out");
int fr[200];
int main() {
  string c;
  char exista[32];
  cin >> c;
  int distincte = 0;
  for (int i = 0; i < c.size(); ++i) {
    if (fr[c[i]] < 3) ++fr[c[i]];
    if (fr[c[i]] == 1) {
      ++distincte;
      exista[distincte] = c[i];
    }
    if (distincte >= 5) break;
  }
  if (distincte == 1 || distincte >= 5) {
    cout << "No";
    return 0;
  }
  if (distincte == 2) {
    if (fr[exista[1]] >= 2 && fr[exista[2]] >= 2)
      cout << "Yes";
    else
      cout << "No";
  } else if (distincte == 3) {
    if (fr[exista[1]] >= 2 || fr[exista[2]] >= 2 || fr[exista[3]] >= 2)
      cout << "Yes";
    else
      cout << "No";
  } else if (distincte == 4) {
    cout << "Yes";
  }
  return 0;
}
