CaesarQWERTY 1.1

#include <iostream>
#include <map>
#include <vector>
#include <stdio.h>
#include <string>

#define ll long long

using namespace std;

map <char, ll> letter;
string qwerty = "qwertyuiopasdfghjklzxcvbnm";
string s;
ll shift;

void mapping() {
    for (ll i = 0; i < 26; i++) {
        letter[qwerty[i]] = i;
    }
}

char transformation(char a, ll cshift) {
    if (cshift == 0) return a;
    ll index = letter[a];
    if (cshift < 0) index += 26;
    return qwerty[index + cshift % 26];
}

int main() {
    //in input file you should write text on the next line after the shift number
    //you can write text on several lines
    //shift number should be in [-4 * 1e18, 4 * 1e18]
    //freopen("inputfilename", "r", stdin);
    //freopen("outputfilename", "w", stdout);
    qwerty += qwerty;
    mapping();
    cin >> shift;
    getline(cin, s);
    while (getline(cin, s)){
        for (auto i : s) {
            if (i >= 'A' && i <= 'Z') {
                cout << toupper(transformation(tolower(i), shift));
            } else if (i >= 'a' && i <= 'z') {
                cout << transformation(i, shift);
            } else {
                cout << i;
            }
        }
        cout << '\n';
    }
    return 0;
}