Problem:
Score : 700 points

Problem Statement

Given is a sequence of N digits a_1a_2\ldots a_N, where each element is 1, 2, or 3.
Let x_{i,j} defined as follows:

x_{1,j} := a_j \quad (1 \leq j \leq N)

x_{i,j} := | x_{i-1,j} - x_{i-1,j+1} | \quad (2 \leq i \leq N and 1 \leq j \leq N+1-i)

Find x_{N,1}.

Constraints

2 \leq N \leq 10^6

a_i = 1,2,3 (1 \leq i \leq N)

Input

Input is given from Standard Input in the following format:

N
a_1a_2\ldotsa_N

Output

Print x_{N,1}.

Sample Input 1

4
1231

Sample Output 1

1

x_{1,1},x_{1,2},x_{1,3},x_{1,4} are respectively 1,2,3,1.

x_{2,1},x_{2,2},x_{2,3} are respectively |1-2| = 1,|2-3| = 1,|3-1| = 2.

x_{3,1},x_{3,2} are respectively |1-1| = 0,|1-2| = 1.

Finally, x_{4,1} = |0-1| = 1, so the answer is 1.

Sample Input 2

10
2311312312

Sample Output 2

0

Solution in Python (3.4.3) (judge verdict: Time Limit Exceeded)

# -*- coding: utf-8 -*-
"""
Created on Sun Mar 22 13:54:24 2020

@author: naoki
"""
import sys
#f = open("C:/Users/naoki/Desktop/Atcoder/input.txt")
N = int(input())
a = list(map(lambda x:int(x)-1,list(input())))
   
all_odd = 0
kai = [0] * N

if (0 not in a) and (1 not in a):
    print(0)
    sys.exit()
if (1 not in a) and (2 not in a):
    print(0)
    sys.exit()
if (0 not in a) and (2 not in a):
    print(0)
    sys.exit()
    
for k in range(1,N):
    count = 0
    p = k
    for _ in range(N):
        if p % 2 == 1:
            kai[k] = kai[k-1] + count
            break
        p = p/2
        count += 1

all_num = 0
for k in range(N):
    if kai[-1] <= kai[k] + kai[N-1-k] and a[k] == 1:
        all_num += 1

if all_num % 2 == 1:
    print(1)
elif 1 in a:
    print(0)
else:
    for i in range(N):
        a[i] = a[i]/2
    for k in range(N):
        if kai[-1] <= kai[k] + kai[N-1-k] and a[k] == 1:
            all_num += 1
    if all_num % 2 == 1:
        print(2)
    else:
        print(0)