
# 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:

A, B = list(map(int, input().split()))



cnt = 0

for n in range(A, B+1):

    n_s = str(n)

    n_s_rvs = n_s[::-1]

    if n_s == n_s_rvs:

        cnt += 1



print(cnt)


# optimized version of the same code:

A, B = list(map(int, input().split()))



cnt = 0

for n in range(A, B+1):

    if n//10000 == n%10 and (n//1000)%10 == (n//10)%10:

        cnt += 1



print(cnt)

A, B = list(map(int, input().split()))
cnt = 0
for n in range(A, B + 1):
    n_s = str(n)
    n_s_rvs = n_s[::-1]
    if n_s == n_s_rvs:
        cnt += 1
print(cnt)

A, B = list(map(int, input().split()))
cnt = 0
for n in range(A, B + 1):
    if n // 10000 == n % 10 and (n // 1000) % 10 == (n // 10) % 10:
        cnt += 1
print(cnt)

-    n_s = str(n) -    n_s_rvs = n_s[::-1] -    if n_s == n_s_rvs: +    if n // 10000 == n % 10 and (n // 1000) % 10 == (n // 10) % 10: