# Write a function to replace all spaces in the given string with character * list item * list item * list item * list item '%20'.
MAX = 1000


def replace_spaces(string):
    string = string.strip()
    i = len(string)
    space_count = string.count(" ")
    new_length = i + space_count * 2
    if new_length > MAX:
        return -1
    index = new_length - 1
    string = list(string)
    for f in range(i - 2, new_length - 2):
        string.append("0")
    for j in range(i - 1, 0, -1):
        if string[j] == " ":
            string[index] = "0"
            string[index - 1] = "2"
            string[index - 2] = "%"
            index = index - 3
        else:
            string[index] = string[j]
            index -= 1
    return "".join(string)
