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: Time Limit Exceeded)


import java.util.Scanner;
public class Main{
	public static void main(String[] args) 
	{
		// TODO Auto-generated method stub
		Scanner in=new Scanner(System.in);
        long a=in.nextLong();
        long b=in.nextLong();
        long c=in.nextLong();
        long ans=0,ctr=1,max=-1;
        while(ctr<=c)
        {
        	ans=(int)((a*ctr)/b)-(int)(a*(int)(ctr/b));
        	if(ans>=max)
        	{
        		max=ans;
        	}
        	ctr++;
        }
        System.out.println(max);
	}

}