A, B, T = map(int, raw_input().split())
mem = {}
def rec(t):
    if t < 0:
        return 0
    if t%A==0 or t%B==0:
        return t
    if t in mem:
        return mem[t]
    mem[t] = min(rec(t-A)+A, rec(t-B)+B)
    return mem[t]

print rec(T)