
# 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:

# -*- coding: utf-8 -*-



import sys

from collections import Counter



def input(): return sys.stdin.readline().strip()

def list2d(a, b, c): return [[c] * b for i in range(a)]

def list3d(a, b, c, d): return [[[d] * c for j in range(b)] for i in range(a)]

def list4d(a, b, c, d, e): return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]

def ceil(x, y=1): return int(-(-x // y))

def INT(): return int(eval(input()))

def MAP(): return list(map(int, input().split()))

def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]

def Yes(): print('Yes')

def No(): print('No')

def YES(): print('YES')

def NO(): print('NO')

sys.setrecursionlimit(10 ** 9)

INF = 10 ** 18

MOD = 10 ** 9 + 7



def fft(A, B):

    """ 

    高速フーリエ変換(FFT)

        A：出現回数をカウントしたリスト

        B：出現回数をカウントしたリスト

    """

    import numpy as np

    from numpy.fft import rfft, irfft



    # 出現数カウント

    MAXA = max(A)

    MAXB = max(B)

    C1 = [0] * (MAXA+1)

    C2 = [0] * (MAXB+1)

    for a in A:

        C1[a] += 1

    for b in B:

        C2[b] += 1

    # max(A)+max(B)より大きい2冪

    L = 1

    k = 0

    while L <= MAXA + MAXB:

        k += 1

        L = 2**k

    # FFT

    res = irfft(rfft(C1, L) * rfft(C2, L), L)

    # 四捨五入して整数に

    res = np.rint(res).astype(np.int64)

    return res



N, M, L = MAP()

A = LIST()

B = LIST()



res = list(fft(A, B))



mn = INF

for i, a in enumerate(res):

    if a != 0:

        mn = i

        break



for _ in range(L):

    x, y, c = MAP()

    x -= 1; y -= 1

    mn = min(mn, A[x] + B[y] - c)

print(mn)


# optimized version of the same code:

# -*- coding: utf-8 -*-



import sys

from collections import Counter



def input(): return sys.stdin.readline().strip()

def list2d(a, b, c): return [[c] * b for i in range(a)]

def list3d(a, b, c, d): return [[[d] * c for j in range(b)] for i in range(a)]

def list4d(a, b, c, d, e): return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]

def ceil(x, y=1): return int(-(-x // y))

def INT(): return int(eval(input()))

def MAP(): return list(map(int, input().split()))

def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]

def Yes(): print('Yes')

def No(): print('No')

def YES(): print('YES')

def NO(): print('NO')

sys.setrecursionlimit(10 ** 9)

INF = 10 ** 18

MOD = 10 ** 9 + 7



N, M, L = MAP()

A = LIST()

B = LIST()



mn = min(A) + min(B)

for _ in range(L):

    x, y, c = MAP()

    x -= 1; y -= 1

    mn = min(mn, A[x] + B[y] - c)

print(mn)

# -*- coding: utf-8 -*-
import sys
from collections import Counter


def input():
    return sys.stdin.readline().strip()


def list2d(a, b, c):
    return [[c] * b for i in range(a)]


def list3d(a, b, c, d):
    return [[[d] * c for j in range(b)] for i in range(a)]


def list4d(a, b, c, d, e):
    return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]


def ceil(x, y=1):
    return int(-(-x // y))


def INT():
    return int(eval(input()))


def MAP():
    return list(map(int, input().split()))


def LIST(N=None):
    return list(MAP()) if N is None else [INT() for i in range(N)]


def Yes():
    print("Yes")


def No():
    print("No")


def YES():
    print("YES")


def NO():
    print("NO")


sys.setrecursionlimit(10**9)
INF = 10**18
MOD = 10**9 + 7


def fft(A, B):
    """
    高速フーリエ変換(FFT)
        A：出現回数をカウントしたリスト
        B：出現回数をカウントしたリスト
    """
    import numpy as np
    from numpy.fft import rfft, irfft

    # 出現数カウント
    MAXA = max(A)
    MAXB = max(B)
    C1 = [0] * (MAXA + 1)
    C2 = [0] * (MAXB + 1)
    for a in A:
        C1[a] += 1
    for b in B:
        C2[b] += 1
    # max(A)+max(B)より大きい2冪
    L = 1
    k = 0
    while L <= MAXA + MAXB:
        k += 1
        L = 2**k
    # FFT
    res = irfft(rfft(C1, L) * rfft(C2, L), L)
    # 四捨五入して整数に
    res = np.rint(res).astype(np.int64)
    return res


N, M, L = MAP()
A = LIST()
B = LIST()
res = list(fft(A, B))
mn = INF
for i, a in enumerate(res):
    if a != 0:
        mn = i
        break
for _ in range(L):
    x, y, c = MAP()
    x -= 1
    y -= 1
    mn = min(mn, A[x] + B[y] - c)
print(mn)

# -*- coding: utf-8 -*-
import sys
from collections import Counter


def input():
    return sys.stdin.readline().strip()


def list2d(a, b, c):
    return [[c] * b for i in range(a)]


def list3d(a, b, c, d):
    return [[[d] * c for j in range(b)] for i in range(a)]


def list4d(a, b, c, d, e):
    return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]


def ceil(x, y=1):
    return int(-(-x // y))


def INT():
    return int(eval(input()))


def MAP():
    return list(map(int, input().split()))


def LIST(N=None):
    return list(MAP()) if N is None else [INT() for i in range(N)]


def Yes():
    print("Yes")


def No():
    print("No")


def YES():
    print("YES")


def NO():
    print("NO")


sys.setrecursionlimit(10**9)
INF = 10**18
MOD = 10**9 + 7
N, M, L = MAP()
A = LIST()
B = LIST()
mn = min(A) + min(B)
for _ in range(L):
    x, y, c = MAP()
    x -= 1
    y -= 1
    mn = min(mn, A[x] + B[y] - c)
print(mn)

- - -def fft(A, B): -    """ -    高速フーリエ変換(FFT) -        A：出現回数をカウントしたリスト -        B：出現回数をカウントしたリスト -    """ -    import numpy as np -    from numpy.fft import rfft, irfft - -    # 出現数カウント -    MAXA = max(A) -    MAXB = max(B) -    C1 = [0] * (MAXA + 1) -    C2 = [0] * (MAXB + 1) -    for a in A: -        C1[a] += 1 -    for b in B: -        C2[b] += 1 -    # max(A)+max(B)より大きい2冪 -    L = 1 -    k = 0 -    while L <= MAXA + MAXB: -        k += 1 -        L = 2**k -    # FFT -    res = irfft(rfft(C1, L) * rfft(C2, L), L) -    # 四捨五入して整数に -    res = np.rint(res).astype(np.int64) -    return res - - -res = list(fft(A, B)) -mn = INF -for i, a in enumerate(res): -    if a != 0: -        mn = i -        break +mn = min(A) + min(B)