C# Solution

    Dictionary<string,uint> phoneList = new Dictionary<string,uint>();

    int entries = int.Parse(Console.ReadLine());

    while(entries > 0)
    {
        string[] entry = Console.ReadLine().Split();
        string name = entry[0];
        uint tel = uint.Parse(entry[1]);

        phoneList.Add(name, tel);

        entries--;
    }

    bool lookUp = true;

    while(lookUp)
    {
        string lookFor = Console.ReadLine();

        if(lookFor == string.Empty || lookFor == null)
        {
            lookUp = false;
        }            
        else
        {
            if(phoneList.ContainsKey(lookFor))
            {
                Console.WriteLine("{0}={1}", lookFor, phoneList[lookFor]);
            }
            else Console.WriteLine("Not found");
        }
    }

Be Aware: After the n lines of phone book entries, there are an unknown number of lines of queries.

One of solutions: while True: try: ... except EOFError: ...

This is my submission in JS

let list = input.split('\n');
    let phoneBook = {};
    const n = parseInt(list[0]);


    for (let i = 1; i <= n; i++) {
        let [name, number] = list[i].split(' ');
        phoneBook[name] = number;
    }

    for (let i = n + 1; i < list.length; i++) {
        let name = list[i];
        if (name in phoneBook) {
            console.log(`${name}=${phoneBook[name]}`);
        } else {
            console.log('Not found');
        }
*     }

im failing in test case1 but passing all the other ones im about to loose it