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 C# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using System.Linq;

class Program
{
	static void Main()
    {
		long[] N = Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray(); 
      	long ans = N[0]*N[2]/N[1];
      	long ans2 = 0;
      	
      	if (N[1]<=N[2]){
      		for (long x = N[1]-1; x <= N[2]; x++){
       			ans = N[0]*x/N[1];
        		if(ans2>ans){
          			ans = ans2;
        		}
        	}
        }
      	Console.WriteLine(ans);
    }
}