
# 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:

import sys

sys.setrecursionlimit(10 ** 6)

# input = sys.stdin.readline    ####

int1 = lambda x: int(x) - 1

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



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

def MI1(): return list(map(int1, input().split()))



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

def LI1(): return list(map(int1, input().split()))

def LLI(rows_number): return [LI() for _ in range(rows_number)]



def printlist(lst, k='\n'): print((k.join(list(map(str, lst)))))

INF = float('inf')



import numpy as np



def solve():

    n = II()

    D = np.zeros((10, 10))



    for i in range(1, n+1):

        s = list(str(i))

        l = int(s[0])

        r = int(s[-1])

        # print(s, l, r)

        D[l][r] += 1

    # print(D)



    ans = 0

    for i in range(10):

        for j in range(10):

            ans += D[i][j] * D[j][i]

    print((int(ans)))



if __name__ == '__main__':

    solve()


# optimized version of the same code:

import sys

sys.setrecursionlimit(10 ** 6)

# input = sys.stdin.readline    ####

int1 = lambda x: int(x) - 1

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



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

def MI1(): return list(map(int1, input().split()))



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

def LI1(): return list(map(int1, input().split()))

def LLI(rows_number): return [LI() for _ in range(rows_number)]



def printlist(lst, k='\n'): print((k.join(list(map(str, lst)))))

INF = float('inf')



def solve():

    n = II()

    D = [[0]*10 for _ in range(10)]



    for i in range(1, n+1):

        s = list(str(i))

        l = int(s[0])

        r = int(s[-1])

        # print(s, l, r)

        D[l][r] += 1

    # print(D)



    ans = 0

    for i in range(10):

        for j in range(10):

            ans += D[i][j] * D[j][i]

    print((int(ans)))



if __name__ == '__main__':

    solve()

import sys

sys.setrecursionlimit(10**6)
# input = sys.stdin.readline    ####
int1 = lambda x: int(x) - 1


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


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


def MI1():
    return list(map(int1, input().split()))


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


def LI1():
    return list(map(int1, input().split()))


def LLI(rows_number):
    return [LI() for _ in range(rows_number)]


def printlist(lst, k="\n"):
    print((k.join(list(map(str, lst)))))


INF = float("inf")
import numpy as np


def solve():
    n = II()
    D = np.zeros((10, 10))
    for i in range(1, n + 1):
        s = list(str(i))
        l = int(s[0])
        r = int(s[-1])
        # print(s, l, r)
        D[l][r] += 1
    # print(D)
    ans = 0
    for i in range(10):
        for j in range(10):
            ans += D[i][j] * D[j][i]
    print((int(ans)))


if __name__ == "__main__":
    solve()

import sys

sys.setrecursionlimit(10**6)
# input = sys.stdin.readline    ####
int1 = lambda x: int(x) - 1


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


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


def MI1():
    return list(map(int1, input().split()))


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


def LI1():
    return list(map(int1, input().split()))


def LLI(rows_number):
    return [LI() for _ in range(rows_number)]


def printlist(lst, k="\n"):
    print((k.join(list(map(str, lst)))))


INF = float("inf")


def solve():
    n = II()
    D = [[0] * 10 for _ in range(10)]
    for i in range(1, n + 1):
        s = list(str(i))
        l = int(s[0])
        r = int(s[-1])
        # print(s, l, r)
        D[l][r] += 1
    # print(D)
    ans = 0
    for i in range(10):
        for j in range(10):
            ans += D[i][j] * D[j][i]
    print((int(ans)))


if __name__ == "__main__":
    solve()

-import numpy as np -    D = np.zeros((10, 10)) +    D = [[0] * 10 for _ in range(10)]