package main

import (
	"fmt"
)

func min(a, b int64) int64 {
	if a < b {
		return a
	}
	return b
}

func resolve(x, y, d int64) int64 {
	ret := int64(0)
	n := min(x, d)
	for i := int64(0); i <= n; i++ {
		j := d - i
		if j <= y {
			ret += 1
		}
	}
	return ret
}

func main() {
	var x, y, d int64

	fmt.Scanf("%d %d %d\n", &x, &y, &d)

	fmt.Println(resolve(x, y, d))
}