#include <iostream>
using namespace std;

int main() {
	int a, b, c, max;
	cin >> a >> b >> c;
	if (c % a == 0) max = c;
	else {
		int n = c / a; // максимальное количество цветков
		max = 0;
		for (int i = 0; i <= (n / 2) && max != c; i++) {
			int first = (n - i) * b +  i * a;
			if (first > max && first <= c) max = first;
			int second = (n - i) * a +  i * b;
			if (second > max && second <= c) max = second;
		} 
	}
	cout << max;
	return 0;
}