<?php

[$x,$y,$z] = explode(" ",trim(fgets(STDIN)));
$ans = 0;

if ($x >= $y && ($x - $y) >= $z) {
    $ans += $y;
    $ans += $z;
}elseif ($x < $y && ($y - $x) >= $z) {
    $ans += $x;
    $ans += $z;
}elseif ($x >= $y && ($x - $y) < $z) {
    $ans += $y;
    $ans += floor(($x -$y + $z)/2);
}else {
    $ans += $x;
    $ans += floor(($y - $x + $z)/2);
}


echo $ans;