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 PyPy3 (7.3.0) (judge verdict: Time Limit Exceeded)

import math
# from collections import Counter

# N = int(input()) # 1行, 単数
# arg = list(map(int, input().split())) # 1行, 配列
# D = Counter(arg) # 出現数カウント

# print('Yes')
# print('No')
# print()


arg = list(map(int, input().split())) # 1行, 配列
A = arg[0]
B = arg[1]
N = arg[2]
maxim = 0

for x in range(N, -1, -1):
  t = math.floor(A * x / B) - A * math.floor(x / B)
  if t > maxim:
    maxim = t

print(maxim)