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 C (Clang 10.0.0) (judge verdict: Wrong Answer)

#include<stdio.h>
int main(){
  int A,B,N;
  int i,x;
  double ans;
  int max=0;
  scanf("%d%d%d",&A,&B,&N);
  for(i=1;i<=N;i++){
    ans=(int)(A*i*1.0/B)-A*(int)(i*1.0/B);
    printf("%f\n",ans);
    if(max<ans){
      max=ans;
      x=i;
    }
  }
  printf("%d",x);
  return 0;
}