#include<iostream>
#include<algorithm>
#include<cmath>
#include<vector>
#include<set>
#include<string>
#include<iomanip>
#include<cstring>
#include<ctime>
#include<unordered_map>
#include<stack>
#include<queue>
//*****************************************************************************************************************
//                .-~~~~~~~~~-._       _.-~~~~~~~~~-.
//            __.'              ~.   .~              `.__
//          .'//                  \./                  \\`.
//        .'//                     |                     \\`.
//      .'// .-~"""""""~~~~-._     |     _,-~~~~"""""""~-. \\`.
//    .'//.-"                 `-.  |  .-'                 "-.\\`.
//  .'//______.============-..   \ | /   ..-============.______\\`.
//.'______________________________\|/______________________________`.
//*****************************************************************************************************************
using namespace std;
const int o = 1e7 + 10;
typedef pair<long, long>ll;
long long a[o], s[o], l1[o], r1[o], c1[o], t = 0;
void num(int l, int r, int c)
{
    a[l] -= c;
    a[r + 1] += c;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    long long n, m;
    cin >> n >> m;
    long long l = 1, r = n;
    long long cmp = 0;
    for (int i = 1; i <= n; i++)
    {
        cin >> l1[i] >> r1[i] >> c1[i];
    }
    while (l <= r)
    {
        for (int i = 1; i <= n; i++)
        {
            s[i] = m;
            a[i] = s[i] - s[i - 1];
        }
        bool fg = 0;
        long long mid = l + r>> 1;
        for (int i = 1; i <= mid; i++)
        {
            num(l1[i], r1[i], c1[i]);
        }
        for (int i = 1; i <= n;i++)
        {
            s[i] = a[i] + s[i - 1];
            if (s[i]<= 0)
            {
                fg = 1;
            }
        }
        if (fg)
        {
            r = mid-1;
            cmp = mid;
        }
        else
        {
            l = mid+1;
        }
    }
    if (cmp!=0)
    {
        cout << cmp;
    }
    else
    {
        cout << "impossible";
    }
}