// Enjoy your stay.

#include <bits/stdc++.h>

#define long long long
#define LOOPVAR_TYPE long

#define all(x) (x).begin(), (x).end()
#define max(x, y) ((x) > (y) ? (x) : (y))
#define min(x, y) ((x) < (y) ? (x) : (y))
#define sz(x) ((LOOPVAR_TYPE)(x).size())
#define foreach(it, X) for(__typeof((X).begin()) it = (X).begin(); it != (X).end(); it++)
#define GET_MACRO(_1, _2, _3, NAME, ...) NAME
#define _rep(i, n) _rep2(i, 0, n)
#define _rep2(i, a, b) for(LOOPVAR_TYPE i = (LOOPVAR_TYPE)(a); i < (LOOPVAR_TYPE)(b); i++)
#define rep(...) GET_MACRO(__VA_ARGS__, _rep2, _rep)(__VA_ARGS__)

#define fir first
#define sec second
#define mp make_pair
#define mt make_tuple
#define pb push_back

const double EPS = 1e-9;
const double PI = acos(-1.0);
const long INF = 1070000000LL;
const long MOD = 1000000007LL;

using namespace std;

typedef istringstream iss;
typedef stringstream sst;
typedef pair<LOOPVAR_TYPE, LOOPVAR_TYPE> pi;
typedef vector<LOOPVAR_TYPE> vi;



int main(){
	cin.tie(0);
	ios_base::sync_with_stdio(0);
	
	long A,B,T;
	cin>>A>>B>>T;
	if(A > T){
		cout<<A<<endl;
		return 0;
	}
	long res = INF*INF;
	if(B >= 40000){
		rep(b,40001){
			long t = b*B;
			if(t >= T) res = min(res, t);
			else res = min(res, t + (T-t + A - 1) / A * A);
		}
	}else{
		rep(b,40001){
			long x = T / B*B;
			long tt = T % B*B;
			long t = b*B;
			if(t >= tt) res = min(res, x*B*B + t);
			else res = min(res, x*B*B + t + (tt-t + A - 1) / A * A);
		}
	}
	cout<<res<<endl;
}