#include <bits/stdc++.h>
int main() {
  int i, a, b, c, k, size;
  scanf("%d %d %d", &a, &b, &c);
  size = a * c / b;
  k = 0;
  for (i = 1; i <= size; i++) {
    k = a * c - b * i;
    if ((b * c) >= k) break;
  }
  printf("%d", i);
  return 0;
}
