#!/usr/bin/perl

use strict;
use warnings;

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

if($y < $x) {
	($x, $y) = ($y, $x);
}

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

print "$count\n";

exit;