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.*;
import java.math.*;
class Main{
  public static void main(String args[])
  {
    Scanner in=new Scanner(System.in);
    double a=in.nextDouble();
    double b=in.nextDouble();
    double n=in.nextDouble();
    if(n<b)
    {
      double x=Math.floor((a*n)/b);
      System.out.print((int)x);
    }
    if(n>=b && n!=1)
    {
      n=n-1;
      double x=Math.floor((a*n)/b);
      System.out.print((int)x);
    }
  
    else if(n==1)
    {
      double v=Math.floor((a*n)/b)-a*Math.floor(n/b);
       System.out.print((int)v);
    }
    
    
  }
}