#include<bits/stdc++.h>
#define ll long long
#define db double
#define taskname ""
#define pb push_back
#define fi first
#define mll map<ll,ll>
#define se second
#define in insert
using namespace std;
const int N=1e6+1;
const int M=1e3+1;
int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	if(fopen(taskname".inp","r"))
	{
		freopen(taskname".inp","r",stdin);
		freopen(taskname".out","w",stdout);
	}
	ll a,b,x;
	cin>>a>>b>>x;
	if(a==x){
		cout<<b<<endl;
	}
	else if(a>x){
		cout<<b<<endl;
	}
	else{
		if(a==1)cout<<x*b<<endl;
		else{
			//cout<<b+x/a*b<<endl;
			if(a==b){
				if(x%b==0) cout<<x<<endl;
				else{
					if(x/b<=x/2) cout<<(x/b+1)*b;
					else cout<<(x/b-1)*b;
				}
			}
			else cout<<b+x/a*b<<endl;
		}
	}
	return(0^0);
}