#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-5;
const int inf = 0x3f3f3f3f3f;
int sans[200];
char a[100010];
int main() {
  int n;
  vector<char> v;
  int z = 'z';
  while (scanf("%s", a) == 1) {
    n = strlen(a);
    int cnt = 0;
    memset(sans, 0, sizeof(sans));
    v.clear();
    for (int i = 0; i < n; i++) {
      if (sans[a[i]] == 0) {
        cnt++;
        v.push_back(a[i]);
      }
      sans[a[i]]++;
    }
    if (cnt <= 1 || cnt >= 5) {
      puts("No");
    } else {
      if (cnt == 2) {
        if (sans[v[0]] >= 2 && sans[v[1]] >= 2) {
          puts("Yes");
        } else
          puts("No");
      } else if (cnt == 3) {
        if (sans[v[0]] == 1 && sans[v[1]] == 1 && sans[v[2]] == 1) {
          puts("No");
        } else
          puts("Yes");
      } else if (cnt == 4) {
        puts("Yes");
      }
    }
  }
  return 0;
}
