#include <cstdlib>
#include <iostream>
#include <cstring>
#include <fstream>
using namespace std;
int main()
{
 
    ifstream instaff ("loginstaff.in"); //creating the stream
    if (!instaff)
    {
        cout << "no file" << endl;
        exit (0);
    }
    char user[10],username[10],subject[30], sub[30] , pass[30];
    cout<<"enter username: ";
    cin.getline(username,10,'\n');//getting the username from the keyboard
    cout<<"enter subject: ";
    cin.getline(subject,30,'\n');//getting the subject from the keyboard
    int i=0;
 
    while(!instaff.eof()) // while not the end of the file 
    {
        instaff.getline(user,10,' '); // get the username from the text file
        instaff.getline(pass,30,' '); // get the password from the text file 
        if(strcmp(user,username)==0) // compare username and the one from the file
        {
            char let;
            while (instaff.get(let)) // take character by character
            {
                sub[i]=let; // assign the letter to the subject array
                i++;// increment the array index for next letter
                if (let==' ') // if the letter is space which means the end of the subject 
                {
                    sub[i]='\0';  // close the subject string
                    i=0; // return the array index to the first position
                    if (strcmp(sub,subject)==0) // compare the input subject with that in the file
                    {
                        cout << "valid"; // if they are same output "valid"
                        return 0; // end the program
                    }
                }
                if (let=='\n') // if the letter is '\n' which means the end of the subject list of that user
                {
                    cout << "not valid" <<endl; // no subjects match 
                    return 0;
                }
           }
           }
        }
        return 0;
}