from sys import stdin

import sys

 

A, B, N = [int(x) for x in stdin.readline().rstrip().split()]

# N, M = [int(x) for x in stdin.readline().rstrip().split()]

# U = input().split()

ans = int((A*N)/B)-A*int(N/B)

ans2=0

if B-1<N:

	ans = int((A*(B-1))/B)-A*int((B-1)/B)

else:

  	ans2=0

    

 

 

print(ans)
from sys import stdin

 

A, B, N = [int(x) for x in stdin.readline().rstrip().split()]

 

ans1 = (A*N)//B-A*(N//B)

 

if B-1<=N:

	ans2 = (A*(B-1))//B

else:

  	ans2=0

 

print((max(ans1,ans2)))
from sys import stdin
import sys

A, B, N = [int(x) for x in stdin.readline().rstrip().split()]
# N, M = [int(x) for x in stdin.readline().rstrip().split()]
# U = input().split()
ans = int((A * N) / B) - A * int(N / B)
ans2 = 0
if B - 1 < N:
    ans = int((A * (B - 1)) / B) - A * int((B - 1) / B)
else:
    ans2 = 0
print(ans)

from sys import stdin

A, B, N = [int(x) for x in stdin.readline().rstrip().split()]
ans1 = (A * N) // B - A * (N // B)
if B - 1 <= N:
    ans2 = (A * (B - 1)) // B
else:
    ans2 = 0
print((max(ans1, ans2)))

-import sys -# N, M = [int(x) for x in stdin.readline().rstrip().split()] -# U = input().split() -ans = int((A * N) / B) - A * int(N / B) -ans2 = 0 -if B - 1 < N: -    ans = int((A * (B - 1)) / B) - A * int((B - 1) / B) +ans1 = (A * N) // B - A * (N // B) +if B - 1 <= N: +    ans2 = (A * (B - 1)) // B -print(ans) +print((max(ans1, ans2)))