f = open('24-1.txt')
s = f.readline()
k = ''
ch = []
for i in range(len(s)):
    if '1' <= s[i] <= '9':
        k += s[i]
    else:
        if k!='':
            if int(k)%2!=0:
                ch += [int(k)]
        k = ''

print(max(ch))