
# 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:

N = int(eval(input()))

X = [[] for i in range(N)]

for i in range(N-1):

    x, y = list(map(int, input().split()))

    X[x-1].append(y-1)

    X[y-1].append(x-1)



P = [-1] * N

DE = [0] * N

Q = [0]

while Q:

    i = Q.pop()

    for a in X[i][::-1]:

        if a != P[i]:

            P[a] = i

            DE[a] = DE[i] + 1

            X[a].remove(i)

            Q.append(a)



def lp(u, v):

    t = 0

    while u != v:

        if DE[u] > DE[v]:

            t += 1 << u-1

            u = P[u]

        elif DE[u] < DE[v]:

            t += 1 << v-1

            v = P[v]

        else:

            t += 1 << u-1

            t += 1 << v-1

            u = P[u]

            v = P[v]

    

    return t



Y = []

M = int(eval(input()))

for _ in range(M):

    a, b = list(map(int, input().split()))

    a, b = a-1, b-1

    Y.append(lp(a, b))



D = {1<<i: i for i in range(50)}

Z = [0] * (1<<M)

ans = 0

CC = [0] * N

BC = [0] * (1<<17)

for m in range(1, 1<<17):

    a = m & (-m)

    BC[m] = BC[m^a] + 1

for m in range(1<<M):

    a = m & (-m)

    if a == m:

        if a == 0:

            Z[m] = 0

        else:

            Z[m] = Y[D[a]]

    else:

        Z[m] = Z[m^a] | Y[D[a]]

    

    aa = Z[m]

    bc = BC[aa % (1<<17)]

    aa >>= 17

    bc += BC[aa % (1<<17)]

    aa >>= 17

    bc += BC[aa]

    CC[N - 1 - bc] += (1 if BC[m%1024] + BC[m>>10] & 1 == 0 else -1)



print((sum([2 ** i * CC[i] for i in range(N)])))

# optimized version of the same code:

N = int(eval(input()))

X = [[] for i in range(N)]

for i in range(N-1):

    x, y = list(map(int, input().split()))

    X[x-1].append(y-1)

    X[y-1].append(x-1)



P = [-1] * N

DE = [0] * N

Q = [0]

while Q:

    i = Q.pop()

    for a in X[i][::-1]:

        if a != P[i]:

            P[a] = i

            DE[a] = DE[i] + 1

            X[a].remove(i)

            Q.append(a)



def lp(u, v):

    t = 0

    while u != v:

        if DE[u] > DE[v]:

            t += 1 << u-1

            u = P[u]

        elif DE[u] < DE[v]:

            t += 1 << v-1

            v = P[v]

        else:

            t += 1 << u-1

            t += 1 << v-1

            u = P[u]

            v = P[v]

    

    return t



Y = []

M = int(eval(input()))

for _ in range(M):

    a, b = list(map(int, input().split()))

    a, b = a-1, b-1

    Y.append(lp(a, b))



def popcnt(n):

    c = (n & 0x5555555555555555) + ((n>>1) & 0x5555555555555555)

    c = (c & 0x3333333333333333) + ((c>>2) & 0x3333333333333333)

    c = (c & 0x0f0f0f0f0f0f0f0f) + ((c>>4) & 0x0f0f0f0f0f0f0f0f)

    c = (c & 0x00ff00ff00ff00ff) + ((c>>8) & 0x00ff00ff00ff00ff)

    c = (c & 0x0000ffff0000ffff) + ((c>>16) & 0x0000ffff0000ffff)

    c = (c & 0x00000000ffffffff) + ((c>>32) & 0x00000000ffffffff)

    return c



D = {1<<i: i for i in range(50)}

Z = [0] * (1<<M)

ans = 0

CC = [0] * N

for m in range(1<<M):

    a = m & (-m)

    if a == m:

        if a == 0:

            Z[m] = 0

        else:

            Z[m] = Y[D[a]]

    else:

        Z[m] = Z[m^a] | Y[D[a]]

    

    CC[N - 1 - popcnt(Z[m])] += (1 if popcnt(m) & 1 == 0 else -1)



print((sum([2 ** i * CC[i] for i in range(N)])))
N = int(eval(input()))
X = [[] for i in range(N)]
for i in range(N - 1):
    x, y = list(map(int, input().split()))
    X[x - 1].append(y - 1)
    X[y - 1].append(x - 1)
P = [-1] * N
DE = [0] * N
Q = [0]
while Q:
    i = Q.pop()
    for a in X[i][::-1]:
        if a != P[i]:
            P[a] = i
            DE[a] = DE[i] + 1
            X[a].remove(i)
            Q.append(a)


def lp(u, v):
    t = 0
    while u != v:
        if DE[u] > DE[v]:
            t += 1 << u - 1
            u = P[u]
        elif DE[u] < DE[v]:
            t += 1 << v - 1
            v = P[v]
        else:
            t += 1 << u - 1
            t += 1 << v - 1
            u = P[u]
            v = P[v]
    return t


Y = []
M = int(eval(input()))
for _ in range(M):
    a, b = list(map(int, input().split()))
    a, b = a - 1, b - 1
    Y.append(lp(a, b))
D = {1 << i: i for i in range(50)}
Z = [0] * (1 << M)
ans = 0
CC = [0] * N
BC = [0] * (1 << 17)
for m in range(1, 1 << 17):
    a = m & (-m)
    BC[m] = BC[m ^ a] + 1
for m in range(1 << M):
    a = m & (-m)
    if a == m:
        if a == 0:
            Z[m] = 0
        else:
            Z[m] = Y[D[a]]
    else:
        Z[m] = Z[m ^ a] | Y[D[a]]
    aa = Z[m]
    bc = BC[aa % (1 << 17)]
    aa >>= 17
    bc += BC[aa % (1 << 17)]
    aa >>= 17
    bc += BC[aa]
    CC[N - 1 - bc] += 1 if BC[m % 1024] + BC[m >> 10] & 1 == 0 else -1
print((sum([2**i * CC[i] for i in range(N)])))

N = int(eval(input()))
X = [[] for i in range(N)]
for i in range(N - 1):
    x, y = list(map(int, input().split()))
    X[x - 1].append(y - 1)
    X[y - 1].append(x - 1)
P = [-1] * N
DE = [0] * N
Q = [0]
while Q:
    i = Q.pop()
    for a in X[i][::-1]:
        if a != P[i]:
            P[a] = i
            DE[a] = DE[i] + 1
            X[a].remove(i)
            Q.append(a)


def lp(u, v):
    t = 0
    while u != v:
        if DE[u] > DE[v]:
            t += 1 << u - 1
            u = P[u]
        elif DE[u] < DE[v]:
            t += 1 << v - 1
            v = P[v]
        else:
            t += 1 << u - 1
            t += 1 << v - 1
            u = P[u]
            v = P[v]
    return t


Y = []
M = int(eval(input()))
for _ in range(M):
    a, b = list(map(int, input().split()))
    a, b = a - 1, b - 1
    Y.append(lp(a, b))


def popcnt(n):
    c = (n & 0x5555555555555555) + ((n >> 1) & 0x5555555555555555)
    c = (c & 0x3333333333333333) + ((c >> 2) & 0x3333333333333333)
    c = (c & 0x0F0F0F0F0F0F0F0F) + ((c >> 4) & 0x0F0F0F0F0F0F0F0F)
    c = (c & 0x00FF00FF00FF00FF) + ((c >> 8) & 0x00FF00FF00FF00FF)
    c = (c & 0x0000FFFF0000FFFF) + ((c >> 16) & 0x0000FFFF0000FFFF)
    c = (c & 0x00000000FFFFFFFF) + ((c >> 32) & 0x00000000FFFFFFFF)
    return c


D = {1 << i: i for i in range(50)}
Z = [0] * (1 << M)
ans = 0
CC = [0] * N
for m in range(1 << M):
    a = m & (-m)
    if a == m:
        if a == 0:
            Z[m] = 0
        else:
            Z[m] = Y[D[a]]
    else:
        Z[m] = Z[m ^ a] | Y[D[a]]
    CC[N - 1 - popcnt(Z[m])] += 1 if popcnt(m) & 1 == 0 else -1
print((sum([2**i * CC[i] for i in range(N)])))

+ + +def popcnt(n): +    c = (n & 0x5555555555555555) + ((n >> 1) & 0x5555555555555555) +    c = (c & 0x3333333333333333) + ((c >> 2) & 0x3333333333333333) +    c = (c & 0x0F0F0F0F0F0F0F0F) + ((c >> 4) & 0x0F0F0F0F0F0F0F0F) +    c = (c & 0x00FF00FF00FF00FF) + ((c >> 8) & 0x00FF00FF00FF00FF) +    c = (c & 0x0000FFFF0000FFFF) + ((c >> 16) & 0x0000FFFF0000FFFF) +    c = (c & 0x00000000FFFFFFFF) + ((c >> 32) & 0x00000000FFFFFFFF) +    return c + + -BC = [0] * (1 << 17) -for m in range(1, 1 << 17): -    a = m & (-m) -    BC[m] = BC[m ^ a] + 1 -    aa = Z[m] -    bc = BC[aa % (1 << 17)] -    aa >>= 17 -    bc += BC[aa % (1 << 17)] -    aa >>= 17 -    bc += BC[aa] -    CC[N - 1 - bc] += 1 if BC[m % 1024] + BC[m >> 10] & 1 == 0 else -1 +    CC[N - 1 - popcnt(Z[m])] += 1 if popcnt(m) & 1 == 0 else -1