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 Python (3.8.2) (judge verdict: Time Limit Exceeded)

# coding: utf-8
# Your code here!
import math
line = list(map(int,input().split()))

A,B,N =line[0],line[1],line[2]

ans = (N+1)//B
if ans ==0:
    print(math.floor(A*N/B)-A*math.floor(N/B))
else:
    kouho =[0 for j in range(ans)]
    for i in range(1,ans+1):
        x= i*B-1
        kouho[i-1]=(math.floor(A*x/B)-A*math.floor(x/B))
    
    kouho.append(math.floor(A*N/B)-A*math.floor(N/B))
    print(max(kouho))