// yukicoder: No.614 壊れたキャンパス
// 2019.5.7 bal4u

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

//// 高速入力
#if 1
#define gc() getchar_unlocked()
#else
#define gc() getchar()
#endif
int in()    // 非負整数の入力
{
	int n = 0, c = gc();
	while (isspace(c)) c = gc();
	do n = 10 * n + (c & 0xf), c = gc(); while (c >= '0');
	return n;
}

//// 優先度付きキュー（ダイクストラ法用）
#define MAX 1000000
typedef struct { long long t; int b, f; } QUE;
QUE que[MAX]; int qsize;

#define PARENT(i) ((i)>>1)
#define LEFT(i)   ((i)<<1)
#define RIGHT(i)  (((i)<<1)+1)

void min_heapify(int i)
{
	int l, r, min;
	QUE qt;

	l = LEFT(i), r = RIGHT(i);
	if (l < qsize && que[l].t < que[i].t) min = l; else min = i;
	if (r < qsize && que[r].t < que[min].t) min = r;
	if (min != i) {
		qt = que[i]; que[i] = que[min]; que[min] = qt;
		min_heapify(min);
	}
}

void deq()
{
	que[0] = que[--qsize];
	min_heapify(0);
}

void enq(int b, int f, long long t)
{
	int i, min;
	QUE qt;

	i = qsize++;
	que[i].t = t, que[i].b = b, que[i].f = f;
	while (i > 0 && que[min = PARENT(i)].t > que[i].t) {
		qt = que[i]; que[i] = que[min]; que[min] = qt;
		i = min;
	}
}

//// ハッシュテーブル
#define HASHSIZ 500009
typedef struct { int b, f; } HASH;
HASH hash[HASHSIZ+5], *hashend = hash + HASHSIZ;

int lookup(int b, int f)
{
	HASH *p = hash + (int)((((long long)b << 32) + f) % HASHSIZ);
	while (p->f) {
		if (p->b == b && p->f == f) return 1;
		if (++p == hashend) p = hash;
	}
	return 0;
}

int insert(int b, int f)
{
	HASH *p = hash + (int)((((long long)b << 32) + f) % HASHSIZ);
	while (p->f) {
		if (p->b == b && p->f == f) return 1;
		if (++p == hashend) p = hash;
	}
	p->b = b, p->f = f;
	return 0;
}

//// 本問題関連
#define MAXB 200005
typedef struct { int me; int b, f; } T; // floor(me), b,f(your bluding/floor)
T *to[MAXB]; int hi[MAXB];
int N;
#define ABS(x) ((x)>=0?(x):-(x))

long long dijkstra(int sb, int sf, int tb, int tf)
{
	int i, b, f, nb, nf;
	long long t, nt;

	enq(sb, sf, 0);
	while (qsize) {
		b = que[0].b, f = que[0].f, t = que[0].t, deq();
		if (b == tb && f == tf) return t;
		if (insert(b, f)) continue;
		for (i = 0; i < hi[b]; i++) {
			nb = to[b][i].b, nf = to[b][i].f;
			if (lookup(nb, nf)) continue;
			nt = t + ABS(to[b][i].me - f);
			enq(nb, nf, nt);
		}
	}
	return -1LL;
}

int main()
{
	int i, k, a, b, c, M, K, S, T;
	int *memo, sz;

	N = in(), M = in(), K = in(), S = in(), T = in();
	memo = malloc(sizeof(int)*M*3);
	sz = 0; for (i = 0; i < M; i++) {
		memo[sz++] = a = in()-1, memo[sz++] = in(), memo[sz++] = in();
		hi[a]++, hi[a+1]++;
	}
	if (hi[N-1]++ == 0) { puts("-1"); return 0; }
	
	for (i = 0; i < N; i++) if (hi[i])
		to[i] = malloc(sizeof(T)*hi[i]);
	memset(hi, 0, sizeof(int)*N);
	i = 0; while (i < sz) {
		a = memo[i++], b = memo[i++], c = memo[i++];
		k = hi[a]++,   to[a  ][k].me = b, to[a  ][k].b = a+1, to[a  ][k].f = c;
		k = hi[a+1]++, to[a+1][k].me = c, to[a+1][k].b = a,   to[a+1][k].f = b;
	}
	k = hi[N-1]++, to[N-1][k].me = to[N-1][k].f = T, to[N-1][k].b = N-1;
	
	printf("%lld\n", dijkstra(0, S, N-1, T));
	return 0;
}