#include <bits/stdc++.h>   using namespace std;   int pot(int x, int y) {     if (y == 0) {       return 1;     } else {       return x * pot(x, y - 1);     }   }   int bin(int x, int y) {     if ((x == 0 && y != 0) || (y == 0 && x != 0)) {       return 1;     } else {       return bin(x, y - 1) + bin(x - 1, y);     }   }   void strlwr(string& s) {     for (int i = 0; (unsigned)i < s.size(); i++) {       if (s[i] >=  A  && s[i] <=  Z ) {         s[i] += 32;       }     }   }   int main() {     ios::sync_with_stdio(false);     cin.tie(nullptr);     int a[26] = {};     int n;     string s;     cin >> s;     n = s.size();     for (int i = 0; i < n; i++) {       a[s[i] -  a ]++;     }     int k = 25;     for (int i = 0; i < n; i++) {       while (a[k] == 0 && k > 0) {         k--;       }       if (s[i] -  a  < k) {         a[s[i] -  a ]--;       }       if (s[i] -  a  == k) {         a[s[i] -  a ]--;         cout << s[i];       }     }     return 0;   }   