
# 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:

k, s = list(map(int, input().split()))

cnt = 0

for i in range(k + 1):

    for j in range(k + 1):

        if i + j > s:

            break

        elif s - i - j <= k:

            cnt += 1

print(cnt)


# optimized version of the same code:

k, s = list(map(int, input().split()))

cnt = 0

for i in range(k + 1):

    for j in range(k + 1):

        if 0 <= s - i - j <= k:

            cnt += 1

print(cnt)

k, s = list(map(int, input().split()))
cnt = 0
for i in range(k + 1):
    for j in range(k + 1):
        if i + j > s:
            break
        elif s - i - j <= k:
            cnt += 1
print(cnt)

k, s = list(map(int, input().split()))
cnt = 0
for i in range(k + 1):
    for j in range(k + 1):
        if 0 <= s - i - j <= k:
            cnt += 1
print(cnt)

-        if i + j > s: -            break -        elif s - i - j <= k: +        if 0 <= s - i - j <= k: