#!/usr/bin/python
input = open('DATA2.txt', 'r')
output = open('OUT2.txt', 'w')
def largeInt():
	larger = -1
	for lines in input.readlines():
		line = lines.split()
		for x in range(len(line[0])):
			if int(line[0][x]) > larger:
				larger = int(line[0][x])
		output.writelines(str(larger))
		output.writelines("\n")
		larger = -1
largeInt()
output.close()