import math



a,b,n = list(map(int,input().split()))



c = 0

ans = 0

for i in range(1,10**7) :

    x = b*i-1

    if x > n :

        x = n

        c = 1

    ans = max(ans,math.floor((a*x)/b)-a*math.floor(x/b))

    if c == 1 :

        break



print(ans)

import math



a,b,n = list(map(int,input().split()))



c = 0

ans = -1

for i in range(1,n//b+2) :

    x = b*i-1

    if x > n :

        x = n

        c = 1

    if ans >= math.floor((a*x)/b)-a*math.floor(x/b) :

        break

    ans = math.floor((a*x)/b)-a*math.floor(x/b)

    if c == 1 :

        break



print(ans)
import math

a, b, n = list(map(int, input().split()))
c = 0
ans = 0
for i in range(1, 10**7):
    x = b * i - 1
    if x > n:
        x = n
        c = 1
    ans = max(ans, math.floor((a * x) / b) - a * math.floor(x / b))
    if c == 1:
        break
print(ans)

import math

a, b, n = list(map(int, input().split()))
c = 0
ans = -1
for i in range(1, n // b + 2):
    x = b * i - 1
    if x > n:
        x = n
        c = 1
    if ans >= math.floor((a * x) / b) - a * math.floor(x / b):
        break
    ans = math.floor((a * x) / b) - a * math.floor(x / b)
    if c == 1:
        break
print(ans)

-ans = 0 -for i in range(1, 10**7): +ans = -1 +for i in range(1, n // b + 2): -    ans = max(ans, math.floor((a * x) / b) - a * math.floor(x / b)) +    if ans >= math.floor((a * x) / b) - a * math.floor(x / b): +        break +    ans = math.floor((a * x) / b) - a * math.floor(x / b)