<?php

$handle = fopen ("php://stdin","r");
fscanf($handle,"%d",$n);
$file = array_map("intval", explode(" ",fgets($handle)));

$i = 0;
$s = 0;
while($i < $n) {
    $i += ($file[$i] + 1);
    $s++;
}
echo $s;

?>