using System.Collections.Generic;
using System;

public class PriorityQueue<T> where T : IComparable
{
	private IComparer<T> _comparer = null;
	private int _type = 0;
	private T[] _heap;
	private int _sz = 0;
	private int _count = 0;
	public PriorityQueue(int maxSize, IComparer<T> comparer)
	{
		_heap = new T[maxSize];
		_comparer = comparer;
	}
	public PriorityQueue(int maxSize, int type = 0)
	{
		_heap = new T[maxSize];
		_type = type;
	}
	private int Compare(T x, T y)
	{
		if (_comparer != null) return _comparer.Compare(x, y);
		return _type == 0 ? x.CompareTo(y) : y.CompareTo(x);
	}
	public void Push(T x)
	{
		_count++;
		var i = _sz++;
		while (i > 0)
		{
			var p = (i - 1) / 2;
			if (Compare(_heap[p], x) <= 0) break;
			_heap[i] = _heap[p];
			i = p;
		}
		_heap[i] = x;
	}
	public T Pop()
	{
		_count--;
		T ret = _heap[0];
		T x = _heap[--_sz];
		int i = 0;
		while (i * 2 + 1 < _sz)
		{
			int a = i * 2 + 1;
			int b = i * 2 + 2;
			if (b < _sz && Compare(_heap[b], _heap[a]) < 0) a = b;
			if (Compare(_heap[a], x) >= 0) break;
			_heap[i] = _heap[a];
			i = a;
		}
		_heap[i] = x;
		return ret;
	}
	public int Count() => _count;
	public T Peek() => _heap[0];
	public bool Contains(T x)
	{
		for (int i = 0; i < _sz; i++) if (x.Equals(_heap[i])) return true;
		return false;
	}
	public void Clear()
	{
		while (this.Count() > 0) this.Pop();
	}
	public IEnumerator<T> GetEnumerator()
	{
		var ret = new List<T>();
		while (this.Count() > 0)
		{
			ret.Add(this.Pop());
		}
		foreach (var r in ret)
		{
			this.Push(r);
			yield return r;
		}
	}
	public T[] ToArray()
	{
		T[] array = new T[_sz];
		int i = 0;
		foreach (var r in this)
			array[i++] = r;
		return array;
	}
}

public class P : IComparable
{
	public int id { get; set; }
	public int score { get; set; }
	public int CompareTo(object obj)
	{
		var x = (P)obj;
		if (this.score > x.score | (this.score == x.score && this.id < x.id)) return 1;
		else if (this.score < x.score | (this.score == x.score && this.id > x.id)) return -1;
		else return 0;
	}
}

public class hello
{
	public static void Main()
	{
		string[] line = Console.ReadLine().Trim().Split(' ');
		var n = int.Parse(line[0]);
		var r = int.Parse(line[1]);
		var L = int.Parse(line[2]);
		if (r == 0) { Console.WriteLine(1); goto exit; }
		getAns(n, r, L);
	exit:;
	}
	static void getAns(int n, int r, int L)
	{
		var pq = new PriorityQueue<P>(r, 1);
		var s = new int[n];
		var t = new int[n];
		var tmax = 0;
		var tmaxi = -1;
		string[] line = Console.ReadLine().Trim().Split(' ');
		var id = int.Parse(line[0]) - 1;
		var wt = int.Parse(line[1]);
		var ds = int.Parse(line[2]);
		var pret = wt;
		var pred = id;
		s[id] += ds;
		pq.Push(new P { id = id, score = ds });
		for (int i = 0; i < r - 1; i++)
		{
			line = Console.ReadLine().Trim().Split(' ');
			id = int.Parse(line[0]) - 1;
			wt = int.Parse(line[1]);
			ds = int.Parse(line[2]);
			s[id] += ds;
			t[pred] += wt - pret;
			if (t[pred] > tmax) { tmax = t[pred]; tmaxi = pred; }
			else if (t[pred] == tmax && pred < tmaxi) tmaxi = pred;
			var a = pq.Peek();
			if (a.id == id)
			{
				pq.Pop();
				pq.Push(new P { id = id, score = s[id] });
				a = pq.Peek();
			}
			else
			{
				pq.Push(new P { id = id, score = s[id] });
				a = pq.Peek();
			}
			while (true)
			{
				if (a.score == s[a.id]) break;
				else pq.Pop();
				a = pq.Peek();
			}
			pred = a.id;
			pret = wt;
		}
		var b = pq.Peek();
		while (true)
		{
			if (b.score == s[b.id]) break;
			else pq.Pop();
			b = pq.Peek();
		}
		t[b.id] += L - pret;
		if (t[b.id] > tmax) { tmax = t[b.id]; tmaxi = b.id; }
		else if (t[b.id] == tmax && b.id < tmaxi) tmaxi = b.id;

		Console.WriteLine(tmaxi + 1);
	}
}



Measured memory_bytes: 35364