using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace leghosszabb_béke
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] sor = Console.ReadLine().Split();
            int napok = int.Parse(sor[0]);
            int[] x = new int[napok];
            int n = int.Parse(sor[1]);           
            for (int i = 0; i < n; i++)
            {
                sor = Console.ReadLine().Split();
                x[int.Parse(sor[0])]++;
                x[int.Parse(sor[1])]--;
            }
            int szamlalo = 0;
            int k = 0, v = 0, mh = 0, mi = 0;
            for (int i = 0; i < napok; i++)
            {
                szamlalo += x[i];
                if (szamlalo > 0) k = i + 1;
                else v = i;
                if(v - k > mh)
                { mh = v - k; mi = k; }
            }
            if (mh == 0) Console.WriteLine(-1);
            else Console.WriteLine(mh + " " + (mi+1));
            Console.ReadKey();
        }
    }
}