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: Wrong Answer)

#dt = {} for i in x: dt[i] = dt.get(i,0)+1
#dt = {k:v for k,v in sorted(x.items(), key=lambda i: i[1])}
ipnl = lambda n: [int(input()) for _ in range(n)]
inp = lambda :int(input())
ip = lambda :[int(w) for w in input().split()]
mp = lambda :map(int,input().split())

a,b,n = mp()
x = max(n,min(n,b-1))
ans = a*x//b - a*(x//b)
print(ans)