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: Wrong Answer)

n = int(input())
a = input()
al = []
for i in range(n-1):
    al.append(abs(int(a[i])-int(a[i+1])))
if n == 2:
    print(al[0])
else:
    if 1 in al:
        q = 1
    else:
        q = 2
        for i in range(n-1):
            if al[i] == 2:
                al[i] = 1
    p = 0
    le = len(al)
    if n % 2 == 0:
        p += al[le//2]
    for i in range(le//2):
        p = (p + (al[le//2-1-i]-al[le//2+i+(le%2)])) % 2
    print(p*q)