<?php
    $x = [];
    while ($line = fgets(STDIN)) {
        $x[] = explode(" ", trim($line)); //各行の値を変数xに代入、保管
    }
    
    $pos = 1;
    $flg = true;
    $hiku_flg = false;
    $kaisuu = 1;

    do {
        $dec = decbin($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 += $v;  
        }
        
        $tmp = $pos + $susumu_kazu;
        
        if ($x[0][0] < $tmp) {
            if (!$hiku_flg) {
                $tmp = $pos - $susumu_kazu;
                $hiku_flg = true;
            } else {
                $flg = false;
                echo -1;
            }
        }
        
        if ($x[0][0] >= $tmp) {
            $kaisuu++;
            $pos = $tmp;
        }
        
        if ($x[0][0] == $tmp) {
            $pos = $tmp;
            $flg = false;
            echo $kaisuu;
        }
    } while ($flg);