f = open("24-s1.txt")
a = f.readline()
even_number = 0
ch = ''
for i in range(len(a)):
    if '0' <= a[i] <= '9':
        ch += a[i]
        if int(ch) > even_number:
            if int(ch)%2 == 0:
                even_number = int(ch)
    else:
        ch =''
print(even_number)