package main

import "fmt"

func main() {
	var r, b, w int
	fmt.Scan(&r, &b, &w)

	for w > 0 {
		v := w/2 + 1
		if r < b {
			r += v
		} else {
			b += v
		}
		w -= v
	}
	fmt.Println(min(r, b))
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}