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# (Mono-mcs 6.8.0.105) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


    class Program
    {
        static void Main(string[] args)
        {
            string[] Input = Console.ReadLine().Split(' ');
            int A = int.Parse(Input[0]);
            int B = int.Parse(Input[1]);
            int N = int.Parse(Input[2]);
            for(long i = 0; i <= N; i++){
                
            }
            long count = 1;
            long num = 0;
            do
            {
                
                float a = (A * count) / B;
                float b = count / B;
                float b2 = A * b;
                long n = (long)(Math.Floor(a) - Math.Floor(b2));
                
                if(num < n){
                    num = n;
                }
                count++;
            }while(count <= N);
            Console.WriteLine(num);
            
        }
    }