#include <map>

#include <set>

#include <cmath>

#include <ctime>

#include <stack>

#include <queue>

#include <cstdio>

#include <cctype>

#include <bitset>

#include <string>

#include <vector>

#include <cstring>

#include <iostream>

#include <algorithm>

#include <functional>

#define PI acos(-1)

#define eps 1e-8

#define fuck(x) cout<<#x<<" = "<<x<<endl;

#define FIN freopen("input.txt","r",stdin);

#define FOUT freopen("output.txt","w+",stdout);

//#pragma comment(linker, "/STACK:102400000,102400000")

using namespace std;

typedef long long LL;

typedef pair<int, int> PII;

const int maxn = 1e5+;

const int INF = 0x3f3f3f3f;

const int MOD = 1e9+;

LL gcd(LL a,LL b){return b?gcd(b,a%b):a;}

LL lcm(LL a,LL b){return a/gcd(a,b)*b;}

LL powmod(LL a,LL b,LL MOD){LL ans=;while(b){if(b%)ans=ans*a%MOD;a=a*a%MOD;b/=;}return ans;}

double dpow(double a,LL b){double ans=1.0;while(b){if(b%)ans=ans*a;a=a*a;b/=;}return ans;}

int main(){

#ifndef ONLINE_JUDGE

    FIN

#endif

    LL n;

    cin>>n;

    LL m=n;

    LL cnt=;

    LL tmp=;

    while(m>){

        tmp*=;

        cnt++;

        m/=;

    }

    tmp--;

    LL t1=tmp;

    LL t2=n-t1;

    LL ans=;

    while(t1){

        ans+=t1%;

        t1/=;

    }

    while(t2){

        ans+=t2%;

        t2/=;

    }

    cout<<ans<<endl;

}