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 Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    long a = sc.nextLong();
    long b = sc.nextLong();
    long n = sc.nextLong();
    boolean bool = true;
    long x = 0;
    long tmp = 0;
    long ans = 0;

    while(bool){
      tmp = (a * x / b) - a * (x / b);

      if(tmp > ans){
        ans = tmp;
      }

      if(x == n){
        bool = false;
        break;
      } else if(x + b > n){
        x = n;
      } else if(x + b < n){
        x += b;
      }
    }

    System.out.println(ans);
  }
}