#include <iostream>
#include <cstdio>
#include <iomanip>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <bitset>
#include <stack>
#include <utility>
#include <numeric>
#include <algorithm>
#include <functional>
#include <cctype>
#include <complex>
#include <string>
#include <sstream>
#include <fstream>
#include <cassert>
using namespace std;

//common
typedef long long i64,ll;

#define BR "\n"
#define ALL(c) (c).begin(),(c).end()
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define FOR(i,l,r) for(int i=(l);i<(int)(r);++i)
#define EACH(it,o) for(auto it = (o).begin(); it != (o).end(); ++it)
#define IN(l,v,r) ((l)<=(v) && (v)<(r))

//debug
#ifdef NDEBUG
#define DUMP(x)
#define DUMPLN(x)
#define DEBUG(x)
#define DEBUGLN(x)
#define LINE()
#define LINELN()
#define CHECK(exp,act)
#define STOP(e)
#else
#define DUMP(x)  cerr << #x << " = " << (x)
#define DUMPLN(x)  DUMP(x) <<endl
#define DEBUG(x) DUMP(x) << LINE() << " " << __FILE__
#define DEBUGLN(x) DEBUG(x)<<endl
#define LINE()    cerr<< " (L" << __LINE__ << ")"
#define LINELN()    LINE()<<endl
#define CHECK(exp,act)  if(exp!=act){DUMPLN(exp);DEBUGLN(act);}
#define STOP(e)  CHECK(e,true);if(!(e)) exit(1);
#endif

template<class T> inline string toString(const vector<T>& x) {
	stringstream ss;
	REP(i,x.size()){
		if(i!=0)ss<<" ";
		ss<< x[i];
	}
	return ss.str();
}

template<class T> inline string toString(const vector<vector<T> >& map) {
	stringstream ss;
	REP(i,map.size()){
		if(i!=0)ss<<BR;
		ss<< toString(map[i]);
	}
	return ss.str();
}
template<class K,class V>  string toString(map<K,V>& x) {
	string res;stringstream ss;
	for(auto& p:x)ss<< p.first<<":" << p.second<<" ";
	return ss.str();
}

string BITtoString(int bit){
    stringstream ss;
    while(bit!=0){ss<<(bit%2);bit/=2;}
    string res=ss.str();reverse(ALL(res));
    return res;
}

template<typename T,typename V> inline T pmod(T v,V MOD){
	return (v%MOD+MOD)%MOD;
}


int INF=1<<28;
struct SegmentTree{
	vector<int> dat;
	vector<int> mi;

	int n,size;
	SegmentTree(int _n){
		n=Pow2Fit(_n)<<1;
		size=2*n-1;
		dat=vector<int>(size,-INF);
		mi=vector<int>(size,INF);
	}
	int Pow2Fit(int n){
		  n = n | (n >>  1);n = n | (n >>  2);n = n | (n >>  4);n = n | (n >>  8);n = n | (n >> 16);
		  return n ^ (n >> 1);
	}

	int getDat(int v){
		v+=n-1;
		return dat[v];
	}

	void update(int v,int a){
		v+=n-1;
		dat[v]=a;
		mi[v]=v-(n-1);
		while(v>0){
			int parent=v=(v-1)/2;
			int chl=parent*2+1,chr=parent*2+2;
			if(dat[chl]>=dat[chr])mi[parent]=mi[chl];				
			else mi[parent]=mi[chr];
			dat[parent]=max(dat[chl],dat[chr]);
		}
	}

	int query(int a,int b){
		return query(0,a,b,0,n);
	}

	private:
	int query(int v,int a,int b,int l,int r){
		if(r<=a || b<=l)return -1;//out range
		if(a<=l && r<=b)return mi[v];

		int vl=query(v*2+1,a,b,l,(l+r)/2);
		int vr=query(v*2+2,a,b,(l+r)/2,r);
		if(vl==-1)return vr;
		if(vr==-1)return vl;

		if(dat[vl+(n-1)]>=dat[vr+(n-1)])return vl;
		else return vr;
	}
};

class Task{
	public:
	int d,t,x;
	Task(int d,int t,int x):d(d),t(t),x(x){
	}
};

class Main{
public:
	
	void run(){
		int N,R,L;cin >> N >> R >> L;
		vector<Task> ts;
		REP(i,R){
			int d,t,x;cin >> d >> t >> x;d--;
			ts.push_back(Task(d,t,x));
		}

		vector<int> vs(N);
		SegmentTree seg(N);
		REP(i,N)seg.update(i,0);

		int pt=0;
		REP(i,R){
			vs[seg.query(0,N)]+=ts[i].t-pt;
			pt=ts[i].t;
			seg.update(ts[i].d,seg.getDat(ts[i].d)+ts[i].x);
		}
		vs[seg.query(0,N)]+=L-pt;

		int Mv=0;
		REP(i,N)Mv=max(Mv,vs[i]);
		
		REP(i,N)if(Mv==vs[i]){
			cout <<i+1<<endl;return;
		}

	}
};

 int main(){
	//ios::sync_with_stdio(false);
 	Main().run();
 	return 0;
 }

Measured memory_bytes: 13456