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


int main() {
    int n, m;
    cin >> n >> m;
    vector<int> haboru(n);
    for (int i = 0; i < m; i++) {
        int x, y;
        cin >> x >> y;
        haboru[x-1]++;
        haboru[y]--;
    }

    int cnt = 0, cntmax = 0, temp = 0;
    int ans1;

    for(int i = 1; i < n; i++) {
        haboru[i]+=haboru[i-1];
        if(haboru[i] == 0) {
            cnt++;
        } else {
            if (cnt > cntmax) {
                cntmax = cnt;
                ans1 = temp;
            }
            temp = i+2;
            cnt = 0;
        }
    }
    if (cntmax == 0) {
        cout << -1 << endl;
        return 0;
    }
    cout << cntmax << " " << ans1 << endl;
    return 0;
}