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: Runtime Error)

import java.util.Scanner;
 
class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextInt();
        long B = sc.nextInt();
        long N = sc.nextInt();
        long max = 0;
        
        for(long x  = 0; x <= N; x++) {
        	long tmpMax = (x % B * A -(A * x) % B) / B;
        	if(tmpMax > max) {
        		max = tmpMax;
        	}        	      	
        }
        
        System.out.print(max);
	}
}