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: Runtime Error)

fun main(args: Array<String>) {
    val (a, b, n) = readLine()!!.split(" ").map(String::toInt)
    val max = mutableMapOf<Int, Double>()
    for (i in 1..n) {
        val r = Math.floor(((a * i) / b).toDouble()) + Math.floor((i / b).toDouble())
        max[i] = r
    }

    max.maxBy {
        it.value
    }?.let {
        val r = it.value.toInt()
        println(r)
    }

}