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
from math import floor
A,B,N = map(int,input().split())
maxi = 0
Npower = 0
diff = 0
S = N
while S/10 >= 1:
    Npower += 1
    S /=10
if Npower >= 7:
    for i in range(0,10**6+10**5):
        maxi = max(int((A*i)/B)-A*int(i/B),maxi)
    for i in range(N-2*10**6,N+1):
        maxi = max(int((A*i)/B)-A*int(i/B),maxi)
else:
    for i in range(0,N+1):
        maxi = max(int((A*i)/B)-A*int(i/B),maxi)
print(max(maxi,0))