A,B,T = map(int,raw_input().split())
ans = 1000000001
stack = [0]
while len(stack) != 0:
	hoge = stack.pop()
	if hoge >= T:
		if ans > hoge:
			ans = hoge
		continue
	stack.append(hoge+A)
	stack.append(hoge+B)
print ans