#include <bits/stdc++.h>

using namespace std;

int main()
{
    iostream::sync_with_stdio(0);
    cin.tie();
    int n, k;
    cin >> n >> k;
    bool* a = new bool[n+1] { 0 };
    int m, l;
    for(int i = 0; i < k; i++)
    {
        cin >> m >> l;
        fill(a+m, a+l+1,1);
    }
    int mx = 0;
    int counter = 0;
    int indmx = 0;
    int indcur = 0;
    for(int i = 1; i <= n; i++)
    {
        if(a[i])
        {
            if(mx < counter)
            {
                indmx = indcur;
                mx = counter;
            }
            counter = 0;
        }
        else
        {
            if(counter == 0)
            {
                indcur = i;
                counter++;
            }
            else counter++;
        }
    }
    if(mx < counter)
    {
        mx = counter;
        indmx = indcur;
    }
    if(mx == 0)
    {
        cout << "-1";
    }
    else cout << mx << " " << indmx;
}