#include <bits/stdc++.h>
using namespace std;

int main() {
    int n, m;
    cin >> n >> m;
    int haboruk[n+1] = {0};
    vector<pair<int, int>> a(m);
    for (int i = 0; i < m; i++) {
        cin >> a[i].first >> a[i].second;
        for (int j = a[i].first; j <= a[i].second; j++) {
            haboruk[j]++;
        }
    }
    bool volte = false;
    int maxos = 0, cnt = 0, ans;
    for(int i = 1; i <= n; i++) {
        if (haboruk[i] == 0) {
            cnt++;
            volte = true;
        }
        else {
            cnt = 0;
        }
        if (cnt > maxos) {
            maxos = cnt;
            ans = i - cnt;
        }
    }
    if (!volte) cout << -1 << endl; else
    cout << maxos << " " << ans + 1 << endl;

}