<?php
    function susumu($pos) {
        $dec = decbin($pos); //10進数→2進数変換 
        $dec_arr = str_split($dec); //2進数の値を区切る
        
        $susumu_kazu = 0;
        foreach($dec_arr as $v) {
            $susumu_kazu += intval($v); 
        }
        return $susumu_kazu;
    }
    
    $x = [];
    while ($line = fgets(STDIN)) {
        $x[] = explode(" ", trim($line)); //各行の値を変数xに代入、保管
    }
    
    // 調査対象キュー
    $queue[] = ["position" => 1, "count" => 1];
    
    // 最短手数を保存
    $stock = [];
    $stock[1] = 1;
    
    $max = $x[0][0] + 1;

    do {
        $data = array_shift($queue);
        $count = $data["count"];
        $pos = $data["position"];
        $susumu_kazu = susumu($pos);
        echo $pos . " susumu:" . $susumu_kazu . "\n";
        
        $fwd  = $pos + $susumu_kazu;
        $back = $pos - $susumu_kazu;
        $count++;
        
        if (!isset($stock[$fwd]) && $max >= $fwd) {
            $stock[$fwd] = $count;
            $queue[] = ["position" => $fwd, "count" => $count];
        }
        
        if (!isset($stock[$back]) && $back > 0) {
            $stock[$back] = $count;
            $queue[] = ["position" => $back, "count" => $count];
        }
    } while (count($queue)>0 && $max >= $pos); // キューがある、最大値までいってないとき繰り返す
    
    //var_dump($stock);
 
    if (isset($stock[$x[0][0]])){
        echo $stock[$x[0][0]];
    } else {
        echo -1;
    }