#include<bits/stdc++.h>
using namespace std;
int main()
{
    #define task "apencil"
    if(fopen(task".inp","r"))
    {
        freopen(task".inp","r",stdin);
        freopen(task".out","w",stdout);
    }
    cin.tie(0)->sync_with_stdio(0);
    int A,B,X;
    cin>>A>>B>>X;
    int tongbut=0,tongtien=0;
    while(tongbut<X)
    {
        tongtien+=B;
        tongbut+=A;
    }
    cout<<tongtien;
}