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 PHP (7.4.4) (judge verdict: Wrong Answer)

<?php
//error_reporting(0);
//$N = (int)trim(fgets(STDIN));
//$S = trim(fgets(STDIN));
list($A,$B,$N) = array_map('intval',explode(" ",trim(fgets(STDIN))));
//$s = trim(fgets(STDIN));
//$A = array_map('intval',explode(" ",trim(fgets(STDIN))));

printf("%d\n",floor($A*$N/$B)-$A*floor($N/$B));