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

            cnt+=1

print(cnt)

# optimized version of the same code:

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

a=0

for i in range(0,k+1):

    for j in range(0,k+1):

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

            a+=1

print(a)
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()))
a = 0
for i in range(0, k + 1):
    for j in range(0, k + 1):
        if 0 <= s - i - j <= k:
            a += 1
print(a)

-cnt = 0 -for i in range(k + 1): -    for j in range(k + 1): +a = 0 +for i in range(0, k + 1): +    for j in range(0, k + 1): -            cnt += 1 -print(cnt) +            a += 1 +print(a)