human
Allen is hosting a formal dinner party. 2n people come to the event in n pairs (couples). After a night of fun, Allen wants to line everyone up for a final picture. The 2n people line up, but Allen doesn't like the ordering. Allen prefers if each pair occupies adjacent positions in the line, as this makes the picture more aesthetic.

Help Allen find the minimum number of swaps of adjacent positions he must perform to make it so that each couple occupies adjacent positions in the line.

Input

The first line contains a single integer n (1 ≤ n ≤ 100), the number of pairs of people.

The second line contains 2n integers a_1, a_2, ..., a_{2n}. For each i with 1 ≤ i ≤ n, i appears exactly twice. If a_j = a_k = i, that means that the j-th and k-th people in the line form a couple.

Output

Output a single integer, representing the minimum number of adjacent swaps needed to line the people up so that each pair occupies adjacent positions.

Examples

Input

4
1 1 2 3 3 2 4 4

Output

2

Input

3
1 1 2 2 3 3

Output

0

Input

3
3 1 2 3 1 2

Output

3

Note

In the first sample case, we can transform 1 1 2 3 3 2 4 4 → 1 1 2 3 2 3 4 4 → 1 1 2 2 3 3 4 4 in two steps. Note that the sequence 1 1 2 3 3 2 4 4 → 1 1 3 2 3 2 4 4 → 1 1 3 3 2 2 4 4 also works in the same number of steps.

The second sample case already satisfies the constraints.
therefore we need 0 swaps.

Can you provide a Python program to find the minimum number of swaps of adjacent positions he must perform to make it so that each couple occupies adjacent positions in the line?
assistant
#Here is Python program to find the minimum number of swaps of adjacent positions he must perform to make it so that each couple occupies adjacent positions in the line.

#from fractions import Fraction
from collections import defaultdict
from math import*
import os
import sys
from io import BytesIO, IOBase
from heapq import nlargest
BUFSIZE = 8192

class FastIO(IOBase):
    newlines = 0 
    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None
 
    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()
 
    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()
 
    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)
class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")

sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)

def input(): return sys.stdin.readline().rstrip("\r\n")
#-------------above part copied---------------thanks kriish---------

def changearray(j,i):
    b=arr[i]
    for k in range(i,j,-1):
        arr[k]=arr[k-1]
    arr[j]=b

def checker(j,x):
    for i in range(j+1,n+n):
      ...