package main

import (
	"fmt"
)

func min(x, y int64) int64 {
	if y < x {
		return y
	}
	return x
}

func main() {
	var x, y, d, z int64
	fmt.Scan(&x, &y, &d)
	for i := int64(0); i <= x; i++ {
		dy := d - i
		if 0 <= dy && dy <= y {
			z++
		}
	}
	fmt.Println(z)
}