
# 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()))



ans = 0

for x in range(k+1):

  for y in range(k+1):

    if 0<=s-x-y<=k:

      ans += 1

      

print(ans)

# optimized version of the same code:

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

ans=0

for i in range(k+1):

  num=s-i

  for j in range(min(num+1,k+1)):

    if 0<=num-j<=k:

      ans+=1

print(ans)
k, s = list(map(int, input().split()))
ans = 0
for x in range(k + 1):
    for y in range(k + 1):
        if 0 <= s - x - y <= k:
            ans += 1
print(ans)

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

-for x in range(k + 1): -    for y in range(k + 1): -        if 0 <= s - x - y <= k: +for i in range(k + 1): +    num = s - i +    for j in range(min(num + 1, k + 1)): +        if 0 <= num - j <= k: