
# 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 i in range(k+1):

    for j in range(k+1):

        z=s-i-j

        if 0<=z<=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):

    for j in range(k+1):

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

            ans+=1

print(ans)

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

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

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