#pragma GCC optimize ("O3")
#include <iostream>
#include <iomanip>
#include <istream>
#include <ostream>
#include <sstream>
#include <iterator>
#include <vector>
#include <algorithm>
#include <queue>
#include <deque>
#include <list>
#include <stack>
#include <map>
#include <unordered_map>
#include <set>
#include <bitset>
#include <utility>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <ctime>
#include <cctype>
#include <cstdlib>
#define IINF 10e8
#define INF 10000000000000
#define MOD 1000000007
#define mod 1000000007
#define REP(i, a, n) for (ll i = a; i < (ll)(n); i++)
#define REPE(i, a, n) for (ll i = a; i <= (ll)(n); i++)
#define Endl endl
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define eb emplace_back
#define mmax(x,y)(x>y?x:y)
#define mmin(x,y)(x<y?x:y)
#define chmax(x,y) x=mmax(x,y)
#define chmin(x,y) x=mmin(x,y)
#define all(x) (x).begin(),(x).end()
#define siz(x) (ll)(x).size()
#define PI acos(-1.0)
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;
typedef long double ld;
typedef pair<int,int>Pin;
typedef pair<ll,ll>Pll;
template<class T> using V=vector<T>;
long long GCD(long long a, long long b) {return b?GCD(b,a%b):a;}
long long LCM(long long a, long long b) {return a/GCD(a,b)*b;}
int dx[4]={-1,0,1,0};
int dy[4]={0,-1,0,1};
int ddx[8]={-1,0,1,0,1,1,-1,-1};
int ddy[8]={0,-1,0,1,1,-1,1,-1};
ll cmp1(pair<ll,ll>a,pair<ll,ll> b){
        if(a.se!=b.se)
        return a.se<b.se;
        else
        return a.fi<b.fi;
}
//----------------------------------------------------------------------
struct HuffmanNode{     //构建哈夫曼节点
    char character;
    ll frequency;
    HuffmanNode *lchild,*rchild;
    HuffmanNode():character(0),frequency(0),lchild(NULL),rchild(NULL){}
};
typedef HuffmanNode *HTNode;
 
struct cmp{          //重定义排序
    bool operator()(HuffmanNode *a,HuffmanNode *b)
    {
        return a->frequency > b->frequency;
    }
};
//----------------------------------------------------------------------
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    //-------------------------------  
    //ll begin_time=clock();
    //-------------------------------
    string s;cin>>s;
    priority_queue<HTNode,vector<HTNode>,cmp> pq;
    map<char,ll>m;
    int cnt=0;
    for(ll i=0;i<s.length();i++){
        m[s[i]]++;
    }
    for(char c='a';c<='z';c++){
        if(m[c])cnt++;
    }
    if(cnt==1){
        cout<<s.length()<<endl;
        return 0;
    }
    for(char c='a';c<='z';c++){
        if(m[c]){
            HTNode tmpNode = new HuffmanNode;
            tmpNode->character=c;
            tmpNode->frequency=m[c];
            pq.push(tmpNode);
        }
    }
    ll BT = 0;
    while(pq.size()>1)
    {
        HTNode tmp1 = new HuffmanNode;  //获得频率最小的两个节点进行合并
        tmp1 = pq.top();
        pq.pop();
        HTNode tmp2 = new HuffmanNode;
        tmp2 = pq.top();
        pq.pop();
        HTNode tmp = new HuffmanNode;
        tmp->frequency = tmp1->frequency +tmp2->frequency;
        tmp->lchild = tmp1;
        tmp->rchild = tmp2;
        BT +=  tmp1->frequency + tmp2->frequency;
        pq.push(tmp);                 //每一次对priority_queue进行操作都会自动更新排序
    }
    cout << BT << endl;
    //-------------------------------  
    //ll end_time=clock();cout<<"time="<<end_time-begin_time<<"ms"<<endl;
    //-------------------------------
    return 0;
}
//----------------------------------------------------------------------















































Measured memory_bytes: 3384