#include <iostream>
#include <vector>

using namespace std;

using ll = long long;

void cypher(){
    ll num,NUM;
    cout << "Put a number, which you want to cypher: ";
    cin >> num;
    NUM = num;
    string s_num;
    while(num > 0){
        ll k = num % 10;
        s_num += (k + 7)%10 + '0';
        num /= 10;
    }
    reverse(s_num.begin(),s_num.end());
    swap(s_num[0],s_num[2]);
    swap(s_num[1],s_num[3]);
    cout << "Number before cyphering: " << NUM<< "\nNumber after cyphering: " << stoll(s_num);
}

void decypher(){
    ll num,NUM;
    cout << "Put a number, which you want to cypher: ";
    cin >> num;
    NUM = num;
    string s = to_string(num),ans,s_num;
    while(s_num.length() + s.length() < 4)
        s_num += '0';
    s_num += s;
    swap(s_num[0],s_num[2]);
    swap(s_num[1],s_num[3]);
    for(auto &i: s_num){
        ll k = i - '0';
        k - 7 >= 0 ? ans += (k-7) + '0' : ans += (k+3) + '0';
    }
    cout << "Number before decyphering: " << NUM << "\nNumber after decyphering: " << stoll(ans);
}

int main() {
    string choice;
    cout << "What do you want to do with your number? Put CYPHER or DECYPHER\n";
    cin >> choice;
    while(choice != "CYPHER" && choice != "DECYPHER"){
        cout << "Incorrect data. Try again. Put CYPHER ot DECYPHER\n";
        cin >> choice;
    }
    choice == "CYPHER" ? cypher() : decypher();
}