Problem: 2^k teams participate in a playoff tournament. The tournament consists of 2^k - 1 games. They are held as follows: first of all, the teams are split into pairs: team 1 plays against team 2, team 3 plays against team 4 (exactly in this order), and so on (so, 2^{k-1} games are played in that phase). When a team loses a game, it is eliminated, and each game results in elimination of one team (there are no ties). After that, only 2^{k-1} teams remain. If only one team remains, it is declared the champion; otherwise, 2^{k-2} games are played: in the first one of them, the winner of the game "1 vs 2" plays against the winner of the game "3 vs 4", then the winner of the game "5 vs 6" plays against the winner of the game "7 vs 8", and so on. This process repeats until only one team remains.

For example, this picture describes the chronological order of games with k = 3:

<image>

Let the string s consisting of 2^k - 1 characters describe the results of the games in chronological order as follows:

  * if s_i is 0, then the team with lower index wins the i-th game; 
  * if s_i is 1, then the team with greater index wins the i-th game; 
  * if s_i is ?, then the result of the i-th game is unknown (any team could win this game). 



Let f(s) be the number of possible winners of the tournament described by the string s. A team i is a possible winner of the tournament if it is possible to replace every ? with either 1 or 0 in such a way that team i is the champion.

You are given the initial state of the string s. You have to process q queries of the following form: 

  * p c — replace s_p with character c, and print f(s) as the result of the query. 

Input

The first line contains one integer k (1 ≤ k ≤ 18).

The second line contains a string consisting of 2^k - 1 characters — the initial state of the string s. Each character is either ?, 0, or 1.

The third line contains one integer q (1 ≤ q ≤ 2 ⋅ 10^5) — the number of queries.

Then q lines follow, the i-th line contains an integer p and a character c (1 ≤ p ≤ 2^k - 1; c is either ?, 0, or 1), describing the i-th query.

Output

For each query, print one integer — f(s).

Example

Input


3
0110?11
6
5 1
6 ?
7 ?
1 ?
5 ?
1 1


Output


1
2
3
3
5
4

Solution (in PYTHON3):

Solution:
# template begins
#####################################
from io import BytesIO, IOBase
import sys
import math
import os
import heapq
from collections import defaultdict, deque
from math import ceil
from bisect import bisect_left, bisect_left
from time import perf_counter


# region fastio

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")
def mint(): return map(int, input().split())
def mfloat(): return map(float, input().split())
def intin(): return int(input())


#####################################
# template ends
# Use the recursion snippet if heavy recursion is needed (depth>1000)
# If constraints are tight, use 1d arrays instead of 2d, like g[i*m+j] instead of g[i][j]
class Node:
    def __init__(self, a, no):
        self.possible = a
        self.child = None
        self.parent1 = self.parent2 = None
        self.no = no
    def __str__(self):
        return f"{self.possible} winners possible till here, no = {self.no}"

def decrease(a, idx, c, s):
    # r = len(a[0])
    r = len(a[1])
    # level = 0
    level = 1
    while idx>r:
        level += 1
        idx -= r
        r //= 2
    idx -= 1
    current_node = a[level][idx]
    # if current_node.parent1 is not None:
    #     if c=='?':
    #         current_node.possible = current_node.parent1.possible + current_node.parent2.possible
    #     elif c=='1':
    #         current_node.possible = current_node.parent2.possible
    #     else:
    #         current_node.possible = current_node.parent1.possible
    # else:
    #     if c=='?':current_node.possible=2
    #     else:current_node.possible=1
    # ans = current_node.possible
    # print(current_node)
    # current_node = current_node.child
    s[current_node.no] = c
    # l=current_node
    while current_node is not None:
        if s[current_node.no]=='?':
            current_node.possible = current_node.parent1.possible + current_node.parent2.possible
        elif s[current_node.no]=='1':
            current_node.possible = current_node.parent2.possible
        else:
            current_node.possible = current_node.parent1.possible
        # print(current_node)
        ans = current_node.possible
        # l=current_node
        current_node = current_node.child
    # print('last changed', l)
    return ans

def solve():
    n = int(input())
    s = list(input())
    a=[]
    for i in range(-1, n):
        a.append([0]*(1<<(n-1-i)))
    # for i in range(1<<(n-1)):
    #     if s[i]=='?':
    #         # a[0][i] = Node(set((2*i, 2*i+1)))
    #         a[0][i] = Node(2, i)
    #     else:
    #         a[0][i] = Node(1, i)
    for i in range(1<<n):a[0][i]=Node(1, -1)
    pointer = 0
    for level in range(1, n+1):
        for j in range(1<<(n-level)):
            parent_1 = a[level-1][2*j]
            parent_2 = a[level-1][2*j+1]
            if s[pointer]=='?':
                a[level][j] = Node(parent_2.possible+parent_1.possible, pointer)
            elif s[pointer]=='1':
                a[level][j] = Node(parent_2.possible, pointer)
            else:
                a[level][j] = Node(parent_1.possible, pointer)
            a[level][j].parent1 = parent_1
            a[level][j].parent2 = parent_2
            parent_1.child = a[level][j]
            parent_2.child = a[level][j]
            pointer += 1   
            
    q = int(input())
    for _ in range(q):
        idx, c = input().split()
        print(decrease(a, int(idx), c, s))
        # print('DONE')
        # for i in a[1:]:
        #     for j in i:
        #         print(j)
        #     print('---next level---')

def main():
    # t = int(input())
    t = 1
    for _ in range(t):
        solve()


if __name__ == "__main__":
    start_time = perf_counter()
    main()
    print(perf_counter()-start_time, file = sys.stderr)