#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <tuple>
#include <random>
using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int inf = 1e9 + 9;
const ll mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);

ll a, b, t;

ll solve() {
    ll res = 1e18;
    if (a > 1e6) {
        for (int i = 0; i <= 1000; i++)
            for (int j = 0; j <= 1000; j++)
                if (a * i + b * j >= t)
                    res = min(res, a * i + b * j);
    } else {
        bool used[a+1];
        memset(used, false, sizeof(used));
        int i = 0;
        while (b * i <= t && !used[(t-b*i)%a]) {
            if ((t-b*i)%a == 0) {
                return t;
            }
            ll v = b * i + a * ((t-b*i)/a+1);
            res = min(res, v);
            used[(t-b*i)%a] = true;
            i++;
        }
        if (b * i > t)
            res = min(res, b * i);
    }
    return res;
}

void input() {
    cin >> a >> b >> t;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    input();
    cout << solve() << endl;
}