#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;
    for(int a0 = 0; a0 < q; a0++){
        int c;
        cin>>c;
        if(c==1){
            int i ,j,t;cin>>i>>j>>t;
            string news=s.substr(0,i);
            for(int h=i;h<=j;h++){
                int x=s[i]-97+t;
                x=x%26;
                x=x+97;char sd=x;
                news+=sd;
            }
            news=news+s.substr(j+1);
            s=news;
        }
        else {
            int i,j;
            cin>>i>>j;
            string news=s.substr(i,j-i+1);
           int len=news.length();
            vector<int>a(26,0);
            for(int k=0;k<len;k++)a[news[k]-97]++;
            int sum=0;
            for(int o=0;o<26;o++){if(a[o]>0)sum++;}
            for(int o=2;o<=len;o++){
                if(o%2==1){
                    
                }
                else {
                    
                }
            }
            cout<<sum<<endl;
        }
        // your code goes here
    }
    return 0;
}