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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

/** 
 *  Author : Parth Prajapati aka (PARTH_4399, hungry_chef)
 *  Institute : Pandit Deendayal Petroleum University
 **/
#include<bits/stdc++.h>

using namespace std; 

#define start_cooking int main()
#define food_is_ready return 0;
#define main_ingredient_added ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);

start_cooking
{
    main_ingredient_added
    //start with your recipe
    long long a, b, n;
    cin>>a>>b>>n;
    long long k;
    if(n%b == 0)
        k = n - 1;
    else
        k = n;
    cout<<(a*k)/b - a*(k/b);
    food_is_ready
}