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:
'''
from bisect import bisect,bisect_left

from collections import *
from heapq import *
from math import gcd,ceil,sqrt,floor,inf,pi

from itertools import *
from operator import add,mul,sub,xor,truediv,floordiv
from functools import *'''


#----------------------------------------------------------------------
import os
import sys

from io import BytesIO, IOBase
# 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)
input = lambda: sys.stdin.readline().rstrip("\r\n")
 

#------------------------------------------------------------------------
def RL(): return map(int, sys.stdin.readline().split())
def RLL(): return list(map(int, sys.stdin.readline().split()))
def N(): return int(input())
def A(n):return [0]*n
def AI(n,x): return [x]*n
def A2(n,m): return [[0]*m for i in range(n)]
def G(n): return [[] for i in range(n)]
def GP(it): return [[ch,len(list(g))] for ch,g in groupby(it)]
#------------------------------------------------------------------------


from types import GeneratorType
 
 
def bootstrap(f, stack=[]):
    def wrappedfunc(*args, **kwargs):
        if stack:
            return f(*args, **kwargs)
        else:
            to = f(*args, **kwargs)
            while True:
                if type(to) is GeneratorType:
                    stack.append(to)
                    to = next(to)
                else:
                    stack.pop()
                    if not stack:
                        break
                    to = stack[-1].send(to)
            return to
 
    return wrappedfunc

mod=10**9+7
farr=[1]
ifa=[]
 
def fact(x,mod=0):
    if mod:
        while x>=len(farr):
            farr.append(farr[-1]*len(farr)%mod)
    else:
        while x>=len(farr):
            farr.append(farr[-1]*len(farr))
    return farr[x]
 
def ifact(x,mod):
    global ifa
    fact(x,mod)
    ifa.append(pow(farr[-1],mod-2,mod))
    for i in range(x,0,-1):
        ifa.append(ifa[-1]*i%mod)
    ifa.reverse()
 
def per(i,j,mod=0):
    if i<j: return 0
    if not mod:
        return fact(i)//fact(i-j)
    return farr[i]*ifa[i-j]%mod
    
def com(i,j,mod=0):
    if i<j: return 0
    if not mod:        
        return per(i,j)//fact(j)
    return per(i,j,mod)*ifa[j]%mod
 
def catalan(n):
    return com(2*n,n)//(n+1)
 
def isprime(n):
    for i in range(2,int(n**0.5)+1):
        if n%i==0:
            return False
    return True

def floorsum(a,b,c,n):#sum((a*i+b)//c for i in range(n+1))
    if a==0:return b//c*(n+1)
    if a>=c or b>=c: return floorsum(a%c,b%c,c,n)+b//c*(n+1)+a//c*n*(n+1)//2
    m=(a*n+b)//c
    return n*m-floorsum(c,c-b-1,a,m-1)

def inverse(a,m):
    a%=m
    if a<=1: return a
    return ((1-inverse(m,a)*m)//a)%m

def popcnt(x):
    ans=0
    while x:
        ans+=1
        x&=x-1
    return ans
 
def lowbit(n):
    return n&-n
 
class BIT:
    def __init__(self,arr):
        self.arr=arr
        self.n=len(arr)-1
        
    def update(self,x,v):
        while x<=self.n:
            self.arr[x]+=v
            x+=x&-x
 
    def query(self,x):
        ans=0
        while x:
            ans+=self.arr[x]
            x&=x-1
        return ans

class ST:
    def __init__(self,arr):#n!=0
        n=len(arr)
        mx=n.bit_length()#取不到
        self.st=[[0]*mx for i in range(n)]
        for i in range(n):
            self.st[i][0]=arr[i]
        for j in range(1,mx):
            for i in range(n-(1<<j)+1):
                self.st[i][j]=max(self.st[i][j-1],self.st[i+(1<<j-1)][j-1])
    def query(self,l,r):
        if l>r:return -inf
        s=(r+1-l).bit_length()-1
        return max(self.st[l][s],self.st[r-(1<<s)+1][s])
        
class DSU:#容量+路径压缩
    def __init__(self,n):
        self.c=[-1]*n
 
    def same(self,x,y):
        return self.find(x)==self.find(y)
 
    def find(self,x):
        if self.c[x]<0:
            return x
        self.c[x]=self.find(self.c[x])
        return self.c[x]
 
    def union(self,u,v):
        u,v=self.find(u),self.find(v)
        if u==v:
            return False
        if self.c[u]>self.c[v]:
            u,v=v,u
        self.c[u]+=self.c[v]
        self.c[v]=u
        return True
 
    def size(self,x): return -self.c[self.find(x)]
    
class UFS:#秩+路径
    def __init__(self,n):
        self.parent=[i for i in range(n)]
        self.ranks=[0]*n
 
    def find(self,x):
        if x!=self.parent[x]:
            self.parent[x]=self.find(self.parent[x])
        return self.parent[x]
 
    def union(self,u,v):
        pu,pv=self.find(u),self.find(v)
        if pu==pv:
            return False
        if self.ranks[pu]>=self.ranks[pv]:
            self.parent[pv]=pu
            if self.ranks[pv]==self.ranks[pu]:
                self.ranks[pu]+=1
        else:
            self.parent[pu]=pv

class UF:#秩+路径+容量，边数
    def __init__(self,n):
        self.parent=[i for i in range(n)]
        self.ranks=[0]*n
        self.size=AI(n,1)
        self.edge=A(n)
 
    def find(self,x):
        if x!=self.parent[x]:
            self.parent[x]=self.find(self.parent[x])
        return self.parent[x]
 
    def union(self,u,v):
        pu,pv=self.find(u),self.find(v)
        if pu==pv:
            self.edge[pu]+=1
            return False
        if self.ranks[pu]>=self.ranks[pv]:
            self.parent[pv]=pu
            self.edge[pu]+=self.edge[pv]+1
            self.size[pu]+=self.size[pv]
            if self.ranks[pv]==self.ranks[pu]:
                self.ranks[pu]+=1
        else:
            self.parent[pu]=pv
            self.edge[pv]+=self.edge[pu]+1
            self.size[pv]+=self.size[pu]
 
def Prime(n):
    c=0
    prime=[]
    flag=[0]*(n+1) 
    for i in range(2,n+1):
        if not flag[i]:
            prime.append(i)
            c+=1
        for j in range(c):
            if i*prime[j]>n: break
            flag[i*prime[j]]=prime[j]
            if i%prime[j]==0: break
    return flag
 
def dij(s,graph):
    d=AI(n,inf)
    d[s]=0
    heap=[(0,s)]
    vis=A(n)
    while heap:
        dis,u=heappop(heap)
        if vis[u]:
            continue
        vis[u]=1
        for v,w in graph[u]:
            if d[v]>d[u]+w:
                d[v]=d[u]+w
                heappush(heap,(d[v],v))
    return d

def bell(s,g):#bellman-Ford
    dis=AI(n,inf)
    dis[s]=0
    for i in range(n-1):
        for u,v,w in edge:
            if dis[v]>dis[u]+w:
                dis[v]=dis[u]+w
    change=A(n)
    for i in range(n):
        for u,v,w in edge:
            if dis[v]>dis[u]+w:
                dis[v]=dis[u]+w
                change[v]=1
    return dis

def lcm(a,b): return a*b//gcd(a,b)
def lis(nums):
    res=[]
    for k in nums:
        i=bisect.bisect_left(res,k)
        if i==len(res):
            res.append(k)
        else:
            res[i]=k
    return len(res)

def RP(nums):#逆序对
    n = len(nums)
    s=set(nums)
    d={}
    for i,k in enumerate(sorted(s),1):
        d[k]=i
    bi=BIT([0]*(len(s)+1))
    ans=0
    for i in range(n-1,-1,-1):
        ans+=bi.query(d[nums[i]]-1)
        bi.update(d[nums[i]],1)
    return ans

def michange(a,b):
    d=defaultdict(deque)
    for i,x in enumerate(b):
        d[x].append(i)
    order=A(len(a))
    for i,x in enumerate(a):
        if not d:
            return -1
        order[i]=d[x].popleft()
    return RP(order)

class DLN:
    def __init__(self,val):
        self.val=val
        self.pre=None
        self.next=None

def nb(i,j,n,m):
    for ni,nj in [[i+1,j],[i-1,j],[i,j-1],[i,j+1]]:
        if 0<=ni<n and 0<=nj<m:
            yield ni,nj

def topo(n):
    q=deque()
    res=[]
    for i in range(1,n+1):
        if ind[i]==0:
            q.append(i)
            res.append(i)
    while q:
        u=q.popleft()
        for v in g[u]:
            ind[v]-=1
            if ind[v]==0:
                q.append(v)
                res.append(v)
    return res

@bootstrap
def gdfs(r,p):
    for ch in g[r]:
        if ch!=p:
            yield gdfs(ch,r)
    yield None


class SMT:
    def __init__(self, size,qf):
        n = 1
        while n < size:
            n <<= 1
        self.size = n
        self.node = [1] * (2 * n)
        self.qf=qf
            

    def q(self,k):
        if self.qf[k]=="?":
            return self.node[k*2]+self.node[k*2+1]
        if self.qf[k]=='0':
            return self.node[k*2]
        return self.node[k*2+1]
 
    def get(self, k):
        return self.node[k + self.size]
 
    def build(self):
        for k in range(self.size - 1, 0, -1):
            self.node[k] = self.q(k)
 
    def update(self, k, x):
        self.qf[k]=x
        while k >= 1:
            self.node[k] = self.q(k)
            k >>= 1
            
 
    def query(self, l, r):#左闭右开
        vl = vr = self.I
        l += self.size
        r += self.size
        while l < r:
            if l & 1:
                vl = self.op(vl, self.node[l])
                l += 1
            if r & 1:
                r -= 1
                vr = self.op(self.node[r], vr)
            l >>= 1
            r >>= 1
        return self.op(vl, vr)

'''
from random import randint,shuffle
def ra(n,a,b):
    return [randint(a,b) for i in range(n)]
'''
t=1
for i in range(t):
    k=N()
    s=input()
    qf=[0]*(1<<k)
    cur=0
    d=[0]*(1<<k)
    for i in range(k-1,-1,-1):
        for j in range(1<<i):
            ind=cur+j
            d[ind]=(1<<i)+j
            qf[d[ind]]=s[ind]
        cur+=1<<i
    smt=SMT(1<<k,qf)
    #print(d)
    #print(qf)
    smt.build()
    q=N()
    for i in range(q):
        ind,ch=input().split()
        cur=d[int(ind)-1]
        smt.update(cur,ch)
        print(smt.node[1])
        
    
    #print(ans)
    
    
'''
sys.setrecursionlimit(200000)
import threading
threading.sta1ck_size(10**8)
t=threading.Thr
ead(target=main)
t.start()
t.join()


'''