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: Wrong Answer)

"""
import math

M,N,Q = map(int,input().split())
a = []

for i in range(Q):
    a.append(list(map(int,input().split())))

print(a)
"""

import math

A,B,N = map(int,input().split())
ans = 0

if N>=B:
    p = B*(N//B)-1
    q =math.floor(A*p/B)-A*math.floor(p/B)
else:
    q =0

if N%B!=0:
    ans=math.floor(A*N/B)-A*math.floor(N/B)
else:
    ans=math.floor(A*(N-1)/B)-A*math.floor((N-1)/B)

print(max(q,ans))