def checkUsername(username):
    f = open('DataLogin.txt','r')

    num_clients=f.readline()
    num_clients=int(num_clients)
    for i in range(1, num_clients+1 ):
        login_user=f.readline()
        login_user=login_user.strip()
        print({login_user})
        login_pass=f.readline()
        login_pass=login_pass.strip()
        print({login_pass})
        if login_user==username:
            return 0
            break
    return 1