#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <cmath>
#include <queue>
#include <stack>
#include <climits>
using namespace std;

using ll = long long;
const int MOD = 1e9 + 7;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m;
    cin >> n >> m;
    vector<bool> days(n+1, 0);
    for(int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        for(int j = a; j <= b; j++) {
            days[j] = 1;
        }
    }

    int maxx = 0;
    int first = -1;
    int run = 0;
    for(int i = 1; i <= n; i++) {
        if(days[i]) {
            run = 0;
        } else {
            run++;
            if(maxx < run) {
                maxx = run;
                first = i-run+1;
            }
        }
    }
    if(first == -1) cout << "-1\n";
    else cout << maxx << " " << first;
    return 0;
}