/*
入力 validation。WA なら OK。
*/

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

int main(){
	registerValidation();
    const int maxn = 1'000'000'000;
    const int maxm = 200'000;
    int n = inf.readInt(1,maxn,"n");
    inf.readSpace();
    int m = inf.readInt(1,maxm,"m");
    inf.readEoln();
    set<pair<int,int>> st;
    for (int i = 0; i < m; i++){
        int l = inf.readInt(1,n,"l");
        inf.readSpace();
        int r = inf.readInt(l,n,"r");
        inf.readEoln();
        st.insert(pair<int,int>(l,r));
    }
    assert(st.size() == m);
	inf.readEof();
	return 0;
}