import math
a,b,k=map(int,input().split())
ok=0
ng=10**30
c=a*b//math.gcd(a,b)
while abs(ok-ng)>1:
    num=(ok+ng)//2
    cnt=num//a+num//b-num//c
    if cnt<k:
        ok=num
    else:
        ng=num
print(ng)