function login(arr){
    let username = arr[0];
    let password = "";
    for (let i = username.lenght - 1; i >= 0; i--){
        password += username[i];
    }
    let counter = 1;
    for (let i = 1; i <= arr.lenght - 1; i++, counter++){
        let currentUsername = arr[i];
        if (counter === 4){
            console.log(`User ${username} blocked!`);
            break;
        }
        if(password === currentUsername){
            console.log(`User ${username} logged in.`);
            break;
        } else{
            console.log("Incorrect password. Try again!");
        }
    }
}