#include <bits/stdc++.h>
using namespace std;

int main() {
    long long A,B,C; cin >> A >> B >> C;

    if(C==1){
        cout << B*A << endl;
        return 0;
    }

    if(A<C){
        cout << B << endl;
        return 0;
    }

    vector<long long> v;
    long long D = C;
    while(A>0){
        v.push_back(A%D);
        A /= D;
    }
    
    reverse(v.begin(),v.end());
    long long ans = 0;
    long long cnt = v[0]*C+v[1];
    if(2*C-2>=cnt) ans += 2;
    else ans += 3;
    ans += (int)v.size() - 2;
    for(int i = 2; i < v.size(); ++i) if(v[i]) ans += 1;
    cout << ans*B << endl; 
    return 0;
}