
# slower version:

s = input()
for i in range(len(s)):
  if i%2 == 0:
    print(s[i], end = '')


# optimized version of the same code:

s = input()
ans = ''
for i in range(len(s)):
  if i % 2 == 0:
    ans += s[i]
print(ans)



# slower version:

import sys



if __name__ == '__main__':

    import doctest

    doctest.testmod()

    S = int(sys.stdin.read())

    h = S / 3600

    m = (S % 3600) / 60

    s = S % 60

    print("%d:%d:%d" % (h, m, s))


# optimized version of the same code:

#!/usr/bin/env python

#-*- coding: utf-8 -*-



# http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ITP1_1_D



if __name__ == '__main__':

    S = int(input())

    h = S / 3600

    m = (S % 3600) / 60

    s = S % 60

    print("%d:%d:%d" % (h, m, s))

import sys

if __name__ == "__main__":
    import doctest

    doctest.testmod()
    S = int(sys.stdin.read())
    h = S / 3600
    m = (S % 3600) / 60
    s = S % 60
    print("%d:%d:%d" % (h, m, s))

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ITP1_1_D
if __name__ == "__main__":
    S = int(input())
    h = S / 3600
    m = (S % 3600) / 60
    s = S % 60
    print("%d:%d:%d" % (h, m, s))

-import sys - +#!/usr/bin/env python +# -*- coding: utf-8 -*- +# http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ITP1_1_D -    import doctest - -    doctest.testmod() -    S = int(sys.stdin.read()) +    S = int(input())