Rot13 & Rot7 v1.0

#include <iostream>
#include <algorithm>
#include <string>

using namespace std;

int main()
{
    string decoded, coded;
    char manip;
    int y = 0;

    getline(cin, decoded);

    coded = decoded;

    while(y <= decoded.size()) {
        for(int i = 0; i <= 4; i++) {
            manip = coded[y];
            manip += 13;
            coded[y] = manip;
            y++;
            if(y % 5 == 0 && y % 10 != 0) {
                for(int u = 0; u <= 4; u++) {
                    manip = coded[y];
                    manip += 7;
                    coded[y] = manip;
                    y++;
                }
            }
        }
    }

    cout << coded << endl;

    decoded = coded;
    y = 0;

    while(y <= coded.size()) {
        for(int i = 0; i <= 4; i++) {
            manip = decoded[y];
            manip -= 13;
            decoded[y] = manip;
            y++;
            if(y % 5 == 0 && y % 10 != 0) {
                for(int u = 0; u <= 4; u++) {
                    manip = decoded[y];
                    manip -= 7;
                    decoded[y] = manip;
                    y++;
                }
            }
        }
    }

    cout << decoded << endl;

    return 0;
}