#!/usr/bin/env python3

# Challenge 282
#
# Task 1: Good Integer
# Submitted by: Mohammad Sajid Anwar
#
# You are given a positive integer, $int, having 3 or more digits.
#
# Write a script to return the Good Integer in the given integer or -1
# if none found.
#
#     A good integer is exactly three consecutive matching digits.
#
# Example 1
#
# Input: $int = 12344456
# Output: 444
#
# Example 2
#
# Input: $int = 1233334
# Output: -1
#
# Example 3
#
# Input: $int = 10020003
# Output: 000

import re
import sys

found = re.search(r'((\d)\2\2+)', sys.argv[1])
if found is None:
    print(-1)
elif len(found.group(1)) != 3:
    print(-1)
else:
    print(found.group(1))