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#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

#define pb push_back
#define pob pop_back
#define eb emplace_back
#define fi first
#define se second
#define turbo ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define mid ((l+r)/2)
#define midLL ((l+r)/2LL)
#define mide ((lo+hi)/2)
#define mideLL ((lo+hi)/2LL)
#define endl '\n'
#define shandom_ruffle random_shuffle
#define lowbit(x) x&(-x)
#define bits(x) __builtin_popcount(x) 
#define mins(se) (*se.begin())
#define maxs(se) (*--se.end())
#define all(x) x.begin(), x.end()
#define log2_floor(i) (i ? __builtin_clzll(1) - __builtin_clzll(i) : -1)
#define siz(cont) ((int)cont.size())
#define each(it, cont) for(auto &it : cont)

using ll = long long;
using pii = std::pair<int, int>;
using pll = std::pair<ll, ll>;
using pli = std::pair<ll, int>;
using pil = std::pair<int, ll>;
using vll = std::vector<pll>;
using vii = std::vector<pii>;
using vi = std::vector<int>;
using vl = std::vector<ll>;
using vvl = std::vector<vl>;
using vvi = std::vector<vi>;
using vvii = std::vector<vii>;
using vli = std::vector<pli>;
using vvli = std::vector<vli>;
using vvll = std::vector<vll>;
using vil = std::vector<pil>;
using vvil = std::vector<vil>;
using vc = std::vector<char>;
using vvc = std::vector<std::vector<char>>;
using vb = std::vector<bool>;
using vvb = std::vector<vb>;

void err() { std::cout << "\n"; fflush(stdout); }
template<class T, class... Ts>
void err(T arg, Ts &... args) {
    std::cout << arg << ' ';
    err(args...);
}

using namespace std;
using namespace __gnu_pbds;

ll n;
string s, ss;

int wr = 0;
gp_hash_table<string, int> pod;

void gen(int i = 0) {
    if (i == n) {
        pod[ss]++;
        if (pod[ss] == 2)
            wr++;
        return;
    }
    gen(i+1);
    ss.pb(s[i]);
    gen(i+1);
    ss.pob();
}

int res() {
    pod.clear();
    wr = 0;
    gen();
    return wr;
}

void solve() {
    int q; cin >> n >> q;
    cin >> s;

    cout << res() << endl;
    
    while (q--) {
        int x; char c; cin >> x >> c;
        s[x-1] = c;
        cout << res() << endl;
    }
}

signed main() { 
    turbo;
    solve();
}