#!/usr/bin/perl

use strict;
use warnings;

my ($x, $y, $d) = split / /, <>;
my $count = 0;

if($x < $y) {
	for(my $i = 0; $i <= $x; $i++) {
		if($d <= $i + $y) {
			$count++;
		}
		if($i == $d) {
			last;
		}
	}
} else {
	for(my $i = 0; $i <= $y; $i++) {
		if($d <= $x + $i) {
			$count++;
		}
		if($i == $d) {
			last;
		}
	}
}


print "$count\n";

exit;