#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int n;
    int q;
    cin >> n >> q;
    string s;
    cin >> s;
    int query,i,j,t;
    for(int a0 = 0; a0 < q; a0++){
        cin>>query;
        if(query==1)
        {
           cin>>i>>j>>t;     
           for(int k=i;k<=j;k++)
               s[k]=(char)(((int)s[k])+t%26);
        }
        else
        {
            cin>>i>>j;
            map<char,int> m;
            int count=0;
            for(int k=i;k<=j;k++)
            {
                m[s[k]]++;
                count++;
            }
            for(map<char,int>::iterator it=m.begin();it!=m.end();it++)
                if(it->second>1)
                    count+=it->second;
            cout<<count<<"\n";
        }
    }
    return 0;
}