Problem:
Score : 400 points

Problem Statement

Given are integers A, B, and N.

Find the maximum possible value of floor(Ax/B) - A × floor(x/B) for a non-negative integer x not greater than N.

Here floor(t) denotes the greatest integer not greater than the real number t.

Constraints

1 ≤ A ≤ 10^{6}

1 ≤ B ≤ 10^{12}

1 ≤ N ≤ 10^{12}

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B N

Output

Print the maximum possible value of floor(Ax/B) - A × floor(x/B) for a non-negative integer x not greater than N, as an integer.

Sample Input 1

5 7 4

Sample Output 1

2

When x=3, floor(Ax/B)-A×floor(x/B) = floor(15/7) - 5×floor(3/7) = 2. This is the maximum value possible.

Sample Input 2

11 10 9

Sample Output 2

9

Solution in C (GCC 9.2.1) (judge verdict: Runtime Error)

#include <stdio.h>

int main()
{
  long int a,b,n,x,i,max;
  
  scanf("%ld %ld %ld", &a, &b, &n);
  long int ans[n];
  
  x = n;
  ans[0] = 0;
  
  i = 1;
  max = ans[0];
  while (x >= 0) {
    ans[i] = (a*x/b) - a*(x/b);
    i++;
    x--;
  }
  i = 1;
  while (max > ans[i]) {
     i++;
  }

  printf("%ld", ans[i]);
  return(0);
}