from math import gcd

a, b, t = map(int, input().split())
if b ** 3 <= t:
    g = gcd(a, b)
    ans = (t + g - 1) // g * g
else:
    ans = 1 << 40
    i = 0
    while b * i <= t:
        j = (t - b * i + a - 1) // a
        ans = min(ans, b * i + a * j)
        i += 1
    ans = min(ans, b * i)
    
print(ans)