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
// Your code here!
fscanf(STDIN,"%d %d %d",$A,$B,$N);
// $r = trim(fgets(STDIN));
$ans = [];
for($x=$N; $x>=0; $x--){
    // $ans[] = floor(($A*$x)/$B - $A * floor($x/$B));
    // var_dump(floor(($A*$x)/$B - $A * floor($x/$B)));
    $t = floor(($A*$x)/$B - $A * floor($x/$B));
    if(empty($ans)){
        $ans[] = $t;
    }elseif(end($ans) >= $t) {
        break;
    }else{
        $ans[] = $t;
    }
}
// var_dump($ans);
print(max($ans));

?>