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
x=input()
x0=x.split()
a=int(x0[0])
b=int(x0[1])
n=int(x0[2])
b0=n%b
b1=0
for i in range(math.floor(n/b)+1):
    if b*i-1>n:
        b1=b*(i-1)-1
        break
q1=math.floor(a*b0/b)-a*math.floor(b0/b)
q2=math.floor(a*b1/b)-a*math.floor(b1/b)
print(max(q1,q2))