C++ multi user login system (improved but w/ errors)

#include <iostream>
#include <vector>
using namespace std;

int main() {
    vector <string> accinfo = {"admin admin"};
    string hpass;
    string hem;
    string hacc;
    string hem2;
    string hpass2;
    int hid2;
    string hacc2;
    int hid;

    int ch = 0;
    int loop = 1;
   while (loop == 1) {
    loop = 0;
    cout << "Welcome to the website!\n\nWould you like to\n1. login\n2. register\n";
    cin >> ch;

    if (ch == 2) {
        cout << "Thank you for regsistering with us!\n\nPlease enter an email:\n";
        cin >> hem;
        cout << "Please enter a password:\n";
        cin >> hpass;
        hacc = hem + " " + hpass;
        accinfo.push_back(hpass);
        cout << "Registration complete!\n";
        hid = accinfo.size() + 1;
        cout << "Your id is " << hid << "\n";
        cout << accinfo.size();
        loop = 1;
    }
    else if (ch == 1) {
        cout << "Please enter your id:\n";
        cin >> hid2;
        hid2 = hid2 - 1;
        cout << "Please enter your email:\n";
        cin >> hem2;
        cout << "Please enter your password:\n";
        cin >> hpass2;
        hacc2 = hem2 + " " + hpass2;
        if (hacc2 == accinfo[hid2]) {
            cout << "Login succesful!\n";
            return 0;
        }
        else if (hacc2 != accinfo[hid2]) {
            cout << "Login failed! Invalid ID?\n";
            loop = 1;
        }

    }
    else {
        cout << "Invalid option\n";
        loop = 1;

    }
   }
}