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#include <bits/stdc++.h>
using namespace std;

#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define ssize(x) int(x.size())
#ifdef DEBUG
auto &operator << (auto &o, pair<auto, auto> p) {
	return o << "(" << p.first << ", " << p.second << ")";
}
auto operator << (auto &o, auto x) -> decltype(x.end(), o) {
	o << "{"; int i = 0;
	for (auto e : x) o << ","+!i++ << e;
	return o << "}";
}
#define debug(X...) cerr << "["#X"]: ", [](auto ...$) {((cerr << $ << "; "), ...) << endl;}(X)
#else
#define debug(...) {}
#endif

using LL = long long;
template<int mod>
struct modular {
	int val;
	modular() { val = 0; }
	modular(const LL& v) {
		val = int((-mod <= v && v < mod) ? (int) v : v % mod);
		if(val < 0) val += mod;
	}
	int to_int() { return val; }
	friend ostream& operator<<(ostream &os, const modular &a) {
#ifdef DEBUG
		constexpr int mx = 1024;
		for(int y = 1; y <= mx; ++y)
			if(a * y <= mx)
				return os << (a * y).val << '/' << y;
			else if(mod - a * y <= mx)
				return os << '-' << (mod - a * y).val << '/' << y;
#endif
		return os << a.val;
	}
	friend istream& operator>>(istream &is, modular &a) {
		return is >> a.val;
	}
	friend bool operator==(const modular &a, const modular &b) {
		return a.val == b.val;
	}
	friend bool operator!=(const modular &a, const modular &b) {
		return !(a == b);
	}
	friend bool operator<(const modular &a, const modular &b) {
		return a.val < b.val;
	}
	friend bool operator<=(const modular &a, const modular &b) {
		return a.val <= b.val;
	}
	modular operator-() const { return modular(-val); }
	modular& operator+=(const modular &m) {
		if((val += m.val) >= mod) val -= mod;
		return *this;
	}
	modular& operator-=(const modular &m) {
		if((val -= m.val) < 0) val += mod;
		return *this;
	}
	modular& operator*=(const modular &m) {
		val = int((LL) val * m.val % mod);
		return *this;
	}
	friend modular qpow(modular a, LL n) {
		if(n == 0) return 1;
		if(n % 2 == 1) return qpow(a, n - 1) * a;
		return qpow(a * a, n / 2);
	}
	friend modular inv(const modular &a) {
		assert(a != 0); return qpow(a, mod - 2);
	}
	modular& operator/=(const modular &m) {
		return (*this) *= inv(m);
	}
	modular operator++(int) {
		modular res = (*this);
		(*this) += 1;
		return res;
	}
	friend modular operator+(modular a, const modular &b) { return a += b; }
	friend modular operator-(modular a, const modular &b) { return a -= b; }
	friend modular operator*(modular a, const modular &b) { return a *= b; }
	friend modular operator/(modular a, const modular &b) { return a /= b; }
};
using mint = modular<998244353>;
int ALPHA = 6;

int solve(const string &s) {
	debug(s);
	int n = ssize(s);

	map<string, int> cnt;
	REP (mask, (1 << n)) {
		string substring = "";
		REP (i, n) if (mask & (1 << i))
			substring += s[i];

		cnt[substring]++;
	}

	debug(cnt);
	int answer = 0;
	for (const auto &[t, c] : cnt)
		if (c >= 2) ++answer;
	return answer;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	int n, q; 
	cin >> n >> q;

	string s; cin >> s;

	cout << solve(s) << '\n';

	while (q--) {
		int pos; char c;
		cin >> pos >> c;
		--pos;

		s[pos] = c;
		cout << solve(s) << '\n';
	}
}