#include <bits/stdc++.h>
#include<cassert>
using namespace std;
using lint = long long;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define ALLR(x) (x).rbegin(), (x).rend()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))
#define FOR(i, begin, end) for(lint i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(lint i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
#define endl '\n'
const lint MOD = 10000ll * 10000ll * 10ll + 7ll;
const lint LINF = 10000ll * 10000ll * 10000ll * 10000ll * 100ll + 7ll;
const int INF = 1000 * 1000 * 1000 + 7;
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> istream &operator>>(istream &is, pair<T, T> &vec){ is >> vec.first >> vec.second; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len, T init) { vec.assign(len, init); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#ifdef LOCAL_JUDGE
# define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << endl;
#else
# define dbg(x)
#endif
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/tag_and_trait.hpp>
using namespace __gnu_pbds; // find_by_order(), order_by_key()
template<typename TK> using pbds_set = tree<TK, null_type, less<TK>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename TK, typename TV> using pbds_map = tree<TK, TV, less<TK>, rb_tree_tag, tree_order_statistics_node_update>;
*/

void solve(){
	int k; cin>>k;
	k = (1<<k) - 1;
	string s; cin>>s;
	reverse(ALL(s));
	vector<lint> tree(2 * (k + 1), 1);
	s = 'A' + s;
	char a;
	auto update = [&](int idx) -> void{
		if(s[idx] == '?'){
			tree[idx] = tree[2 * idx] + tree[2 * idx + 1];
		}else if(s[idx] == '1'){
			tree[idx] = tree[2 * idx];
		}else{
			tree[idx] = tree[2 * idx + 1];
		}
	};

	auto propagate = [&](int idx) -> void{
		s[idx] = a;
		update(idx);
		while(idx >>= 1){
			update(idx);
		}
	};

	IREP(i, k){
		update(i + 1);
	}

	int q; cin>>q;
	while(q--){
		int idx; cin>>idx>>a;
		propagate(k - idx + 1);
		cout<<tree[1]<<endl;
	}
}

int main(){
	fast_ios();
	int T = 1; //cin>>T;
	REP(t, T){
		solve();
	}
	return 0;
}
