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 Kotlin (1.3.71) (judge verdict: Wrong Answer)


fun main(args: Array<String>) {
    val (A, B, N) = readLine()!!.split(" ").map(String::toLong)

    val n = N / B
        if(n * B <= N &&  N <= n * B + listOf(B / A, 1L).max()!!) { (N/ B) * B - listOf(Math.floor(B.toDouble()/ A.toDouble()).toLong(), 1).max()!! } else { N }.let {
           (Math.floor(A.toDouble() * it.toDouble() / B.toDouble()) - A.toDouble() * Math.floor(it.toDouble() / B.toDouble())).toLong()
    }.run(::println)
}