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 Go (1.14.1) (judge verdict: Wrong Answer)

package main

import (
	"fmt"
	"log"
  "math"
)

//floor(Ax/B)−A×floor(x/B
func main() {
	var A,B,N,temp int64
  _, err := fmt.Scanf("%d%d%d", &A,&B,&N)
  temp = 0
  
  for int64(int64(math.Floor(float64(A*temp/B))-float64(A)*math.Floor(float64(temp/B))))<N && temp <N{
    temp++
  }
  
	if err !=nil{
		log.Fatal(err)
  }
  //fmt.Print(A," ",B," ",N)
  fmt.Println(int64(math.Floor(float64(A*temp/B))-float64(A)*math.Floor(float64(temp/B))))
}