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

#define int long long
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
int gcd(int a, int b) { if (!b) return a; return gcd(b, a%b); }
int lcm(int a, int b) { return a / gcd(a, b) * b; }

int A, B, T;
signed main()
{
    cin >> A >> B >> T;
    int maxb = (T + B - 1) / B;
    int minC = 1e10;
    int l = A / gcd(A, B);
    int k = 0;
    RREP(i,maxb+1) {
        int cost = i * B;
        int remain = T - cost;
        int numa = (remain + A - 1) / A;
        cost += numa * A;
        minC = min(minC, cost);
        if (minC == T) break;
        if (k++ > l) break;
    }
    cout << minC << endl;
    return 0;
}