package main

import (
	"bufio"
	"os"
	"strconv"
	"fmt"
)

var s = bufio.NewScanner(os.Stdin)

func next() string {

	s.Split(bufio.ScanWords)
	s.Scan()
	return s.Text()
}
func nextLine() string {
	s.Split(bufio.ScanLines)
	s.Scan()
	if nil != s.Err() {
		panic(s.Err())
	}
	return s.Text()
}

func nextInt() int {
	i, e := strconv.Atoi(next())
	if e != nil {
		panic(e)
	}
	return i
}



func main() {
	A := nextInt()
	B := nextInt()
	T := nextInt()
	mn := T + A
	for i := 0; i*A < T+A; i++ {
		D := T - A * i
		buy := i*A+((D+B-1)/B)*B
		if mn > buy {
			mn = buy
		}
	}
	fmt.Println(mn)

}