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

 

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

 

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

 

if B-1<=N:

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

else:

  	ans2=0

 

print((max(ans1,ans2)))
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

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

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