def check(target):
  cnt = target//A + target//B - target//(A*B//g)
  if cnt<K:
    return False
  return True

from math import gcd
A, B, K = map(int, input().split())
g = gcd(A,B)
low,high = 0,10**18
mid = (low+high)//2
while high-low>1:
  if check(mid):
    high = mid
  else:
    low = mid
  mid = (low+high)//2
ans = high
print(ans)