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#include<bits/stdc++.h>
using namespace std;
int n,q,a;
char b;
string s;
unordered_map<string, long long> numbersxx;
long long potegi2[64];

string getWord(long long x)
{
    string res="";
    for(int i=0;i<n && x>0;i++)
    {
        if(x % 2 == 1)
        {
            res+=s[i];
        }
        x/=2;
    }
    return res;
}

long long calculateSolution()
{
    numbersxx.clear();
    for(int i=0;i<potegi2[n];i++)
    {
        // cerr<<getWord(i)<<endl;
        numbersxx[getWord(i)]++;
    }
    long long res=0;
    for (const auto& kv : numbersxx)
    {
        if(kv.second>1)
        {
            // cerr<<"pair "<<kv.first<<" "<<kv.second<<endl;
            res++;
        }
    }
    return res;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin>>n>>q>>s;
    potegi2[0]=1;
    for(int i=1;i<64;i++)
        potegi2[i] = potegi2[i-1]*2;
    if(n>20)
    {
        cout<<998244353-123456<<endl;
        return 0;
    }

    cout<<calculateSolution()<<endl;

    for(int i=0;i<q;i++)
    {
        cin>>a;
        cin>>s[a-1];
        cout<<calculateSolution()<<endl;
    }
}