#include <bits/stdc++.h>
using namespace std;
pair<int,int> task (vector<int> t,int s){
    int ch = 0,ck = 0,ah=0,ak=0;
    int cnt = 0;
    for(int i = 1;i <= s;i++){
        cnt += t[i];

        if(cnt == 0){
            if(ch == 0) ck = i;
            ch++;
        }else{
            ch = 0;ck = 0;
        }
        if(ah < ch){
            ah = ch;
            ak = ck;
        }
    }
    pair<int,int>ans{ah,ak};
    return ans;
}
int main() {
	int n,m;cin >> n >> m;
    vector<int>v(n+1);
    for(int i = 0;i < m;i++){
        int a,b;cin >> a >> b;
        v[a]++;
        v[b]--;
    }
    pair<int,int>f =task(v,n);
    if(f.first <= 1) cout << -1;
    else cout << f.first-1 << " " << f.second+1;
    //for(int i =1;i <= n;i++) cerr << v[i] << " ";
}