#!/usr/bin/env python
# -*- coding: utf-8 -*-

inputs = ["part1.txt", "input.txt"]


def solve(filename):
    mylist = []
    with open(filename, "r") as fp:
        for line in fp:
            mylist.append(int(line))

    pos = 0
    total = len(mylist) - 1
    steps = 0

    while True:
        oldpos = pos
        oldvalue = mylist[oldpos]
        pos = pos + oldvalue

        if oldvalue >= 3:
            mylist[oldpos] = oldvalue - 1
        else:
            mylist[oldpos] = oldvalue + 1

        steps = steps + 1
        if pos > total:
            break

    return steps


for puzzle in inputs:
    print(puzzle, solve(puzzle))