import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int m = sc.nextInt();
        int k = sc.nextInt();
        int s = sc.nextInt();
        int t = sc.nextInt();
        ArrayList<TreeMap<Integer, Integer>> compress = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            compress.add(new TreeMap<>());
        }
        compress.get(0).put(s, null);
        compress.get(n - 1).put(t, null);
        int[] towers = new int[m];
        int[] froms = new int[m];
        int[] toes = new int[m];
        for (int i = 0; i < m; i++) {
            towers[i] = sc.nextInt() - 1;
            froms[i] = sc.nextInt();
            toes[i] = sc.nextInt();
            compress.get(towers[i]).put(froms[i], null);
            compress.get(towers[i] + 1).put(toes[i], null);
        }
        int idx = 0;
        for (TreeMap<Integer, Integer> map : compress) {
            for (int x : map.keySet()) {
                map.put(x, idx++);
            }
        }
        ArrayList<ArrayList<Path>> graph = new ArrayList<>();
        for (int i = 0; i < idx; i++) {
            graph.add(new ArrayList<>());
        }
        for (TreeMap<Integer, Integer> map : compress) {
            int prev = -1;
            for (int x : map.keySet()) {
                if (prev >= 0) {
                    int y = map.get(x);
                    graph.get(y).add(new Path(y - 1, x - prev));
                    graph.get(y - 1).add(new Path(y, x - prev));
                }
                prev = x;
            }
        }
        for (int i = 0; i < m; i++) {
            int left = compress.get(towers[i]).get(froms[i]);
            int right = compress.get(towers[i] + 1).get(toes[i]);
            graph.get(left).add(new Path(right, 0));
        }
        int sIdx = compress.get(0).get(s);
        int tIdx = compress.get(n - 1).get(t);
        PriorityQueue<Path> queue = new PriorityQueue<>();
        queue.add(new Path(sIdx, 0));
        long[] costs = new long[idx];
        Arrays.fill(costs, Long.MAX_VALUE);
        while (queue.size() > 0) {
            Path p = queue.poll();
            if (costs[p.idx] <= p.value) {
                continue;
            }
            costs[p.idx] = p.value;
            for (Path x : graph.get(p.idx)) {
                queue.add(new Path(x.idx, x.value + p.value));
            }
        }
        if (costs[tIdx] == Long.MAX_VALUE) {
            System.out.println(-1);
        }  else {
            System.out.println(costs[tIdx]);
        }
    }
    
    static class Path implements Comparable<Path> {
        int idx;
        long value;
        
        public Path(int idx, long value) {
            this.idx = idx;
            this.value = value;
        }
        
        public int compareTo(Path another) {
            if (value == another.value) {
                return 0;
            } else if (value < another.value) {
                return -1;
            } else {
                return 1;
            }
        }
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}