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#include <bits/stdc++.h>
#define nl '\n'

using namespace std;
using ll = long long;
const ll mod = 1e9+123;
const ll p = 29;

ll calc(string& s){
	unordered_map<ll, ll> mp;
	mp[0] = 1;
	for(auto c: s){
		vector<pair<ll, ll>> to_add;
		for(auto [hsh, cnt]: mp){
			to_add.push_back({(hsh*p+c-'a'+1)%mod, cnt});
		}
		for(auto [hsh, cnt]: to_add){
			mp[hsh] += cnt;
		}
	}
	ll res = 0;
	for(auto [hsh, cnt]: mp){
		res += cnt > 1;
	}
	return res;
}

int main()
{
	cin.tie(0)->sync_with_stdio(0);
	int n, q;
	cin>>n>>q;
	string s;
	cin>>s;
	cout<<calc(s)<<nl;
	while(q--){
		int pos;
		char c;
		cin>>pos>>c;
		s[pos-1] = c;
		cout<<calc(s)<<nl;
	}
}