#!/usr/bin/env python
# -*- coding: utf-8 -*-
import math

A,B,T = map(int,input().split())
A,B = max(A,B),min(A,B)

total = 0
for i in range(math.ceil(T/A))[::-1]:
    if T - total == 0:
        break
    if T-total > T-(i*A+B*math.ceil((T-i*A)/B)) >= 0:
        total = i*A+B*math.ceil((T-i*A)/B)
print(total if total > 0 else B)