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: Accepted)

//package beg_165;
import java.util.*;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner a = new Scanner(System.in);
		String b = a.nextLine();
		String[] l = b.split(" ");
		
		long[] list = new long[3];
		for (int i=0;i<l.length;i++) {
			list[i]=Long.parseLong(l[i]);
		}
		long x = Math.min(list[1]-1, list[2]);
		
		long A = list[0];
		long B = list[1];
		
		long d = A*x/B;
		long e = x/B;
		e=e*A;
		System.out.println(d-e);
	}

}