#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef long long int ll;

#define xprintf(fmt,...) fprintf(stderr,fmt,__VA_ARGS__)
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}}
#define ALL(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(auto cnt=0ll;(cnt)<(l);++(cnt))
#define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt))
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
#define EPS 1e-12
template<typename T1, typename T2> ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }
template<typename iterator> inline size_t argmin(iterator begin, iterator end) { return distance(begin, min_element(begin, end)); }
template<typename iterator> inline size_t argmax(iterator begin, iterator end) { return distance(begin, max_element(begin, end)); }
template<typename T> T& maxset(T& to, const T& val) { return to = max(to, val); }
template<typename T> T& minset(T& to, const T& val) { return to = min(to, val); }
void bye(string s, int code = 0) { cout << s << endl; exit(0); }
mt19937_64 randdev(8901016);
inline ll rand_range(ll l, ll h) {
    return uniform_int_distribution<ll>(l, h)(randdev);
}

#if defined(_WIN32) || defined(_WIN64)
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#elif __GNUC__
#else
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
namespace {
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T> void input_integer(T& var) {
            var = 0; T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) { input_integer<int>(var); return *this; }
        inline MaiScanner& operator>>(long long& var) { input_integer<long long>(var); return *this; }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiblechar(cc); cc = getchar_unlocked());
            for (; isvisiblechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
        }
        template<typename IT> void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; }
    };
    class MaiPrinter {
    public:
        template<typename T>
        void output_integer(T var) {
            if (var == 0) { putchar_unlocked('0'); return; }
            if (var < 0)
                putchar_unlocked('-'),
                var = -var;
            char stack[32]; int stack_p = 0;
            while (var)
                stack[stack_p++] = '0' + (var % 10),
                var /= 10;
            while (stack_p)
                putchar_unlocked(stack[--stack_p]);
        }
        inline MaiPrinter& operator<<(char c) { putchar_unlocked(c); return *this; }
        inline MaiPrinter& operator<<(int var) { output_integer<int>(var); return *this; }
        inline MaiPrinter& operator<<(long long var) { output_integer<long long>(var); return *this; }
        inline MaiPrinter& operator<<(char* str_p) { while (*str_p) putchar_unlocked(*(str_p++)); return *this; }
        inline MaiPrinter& operator<<(const string& str) {
            const char* p = str.c_str();
            const char* l = p + str.size();
            while (p < l) putchar_unlocked(*p++);
            return *this;
        }
        template<typename IT> void join(IT begin, IT end, char sep = '\n') { for (auto it = begin; it != end; ++it) *this << *it << sep; }
    };
}
MaiScanner scanner;
MaiPrinter printer;


class DGraphE {
public:
    typedef int W_T;
    struct Arc {
        int u, v;
        W_T value;
        Arc(int f = 0, int t = 0, W_T value = 0) :u(f), v(t), value(value) {}
        inline int to(int _v) const { return _v == v ? u : v; }
    };
    size_t n;
    vector<vector<int>> vertex_to;
    //vector<vector<int>> vertex_from;
    vector<Arc> arcs;

    DGraphE(int n = 1) :n(n), vertex_to(n){ }

    void resize(size_t _n) {
        n = _n;
        vertex_to.resize(_n);
    }
    void connect(int from, int to, W_T val = 0) {
        vertex_to[(size_t)from].push_back((int)arcs.size());
        //vertex_from[(size_t)to].push_back((int)edges.size());
        arcs.emplace_back(from, to, val);
    }
};


ll n, m, kei, ss, tt;

map<ll, ll> zip[100010];// [tower][floor] = zipped_floor;
vector<array<ll,3>> paths;

int main() {

    scanner >> n >> m >> kei >> ss >> tt;

    paths.reserve(m);

    repeat(i, m) {
        int a, b, c;
        scanner >> a >> b >> c;
        --a;
        zip[a][b] = 0;
        zip[a+1][c] = 0;
        paths.push_back({ a,b,c });
    }

    zip[0][ss] = 0;
    zip[n-1][tt] = 0;

    ll n_v = 0;
    repeat(i, n) {
        for (auto& p : zip[i]) {
            p.second = n_v++;
        }
    }
    DGraphE g(n_v);

    repeat(i, n) {
        ll last = -1;
        for (auto& p : zip[i]) {
            if (last >= 0) {
                g.connect(p.second, p.second - 1, p.first - last);
                g.connect(p.second - 1, p.second, p.first - last);
            }
            last = p.first;
        }
    }
    for (auto& a : paths) {
        g.connect(zip[a[0]][a[1]], zip[a[0] + 1][a[2]], 0);
    }

    ll start = zip[0][ss];
    ll goal = zip[n - 1][tt];

    priority_queue<pair<ll, int>> pq;
    vector<ll> visited(n_v, (ll)1e18);
    pq.emplace(0, start);
    visited[start] = 0;


    while (!pq.empty()) {
        auto p = pq.top(); pq.pop();
        ll dist = p.first;
        int idx = p.second;

        if (visited[idx] < dist) continue;
        if (idx == goal) {
            cout << dist << endl;
            return 0;
        }
        for (int ei : g.vertex_to[idx]) {
            auto arc = g.arcs[ei];
            if (visited[arc.v] > dist + arc.value) {
                pq.emplace(dist + arc.value, arc.v);
                visited[arc.v] = dist + arc.value;
            }
        }
    }

    cout << -1 << endl;


    return 0;
}