#include <iostream> using namespace std; int main() { /*freopen("run.in", "r", stdin); freopen("run.out", "w", stdout);*/ int x, y, t; scanf("%d,%d,%d", &x, &y, &t); for (int i = t * x; true; ++i) { if (i / x > (i + t * y) / y) { cout<<i - 4; break; } } return 0; }