Basic Encryption

#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define boost ios_base::sync_with_stdio(0)
#define boost1 cin.tie(0)
#define boost2 cout.tie(0)
#define set set<int>s
#define vector vector<ll>v

int main()
{
    boost;boost1;boost2;
    int t,bb,n;
    cin>>t>>bb;
    n=bb-4;
    while(t--)
    {
        string s1;
        cin.ignore();
        getline(cin,s1);
        char ch;
        int letter,k,letter2;
        for(int i=0;i<s1.length();i++)
        {
            if(s1[i]<65 || (s1[i]>90 && s1[i]<97) ||s1[i]>122 || s1[i]==' ')
            {
                s1[i]=s1[i];
            }
            if(s1[i]>=97 && s1[i]<=122)
            {
            letter=s1[i]+n;
            if(letter>122)
            {
                letter=letter-122;
                k=96+letter;
                s1[i]=k;
            }
            else
            {
                s1[i]=letter;
            }
            }
            if(s1[i]>=65 && s1[i]<=90)
            {
            letter2=s1[i]+n;
            if(letter2>90)
            {
                int l;
                letter2=letter2-90;
                l=64+letter2;
                s1[i]=l;
            }
            else
            {
                s1[i]=letter2;
            }
            }
        }
        cout<<s1<<endl;
    }
    return 0;
}