#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <deque>
#include <forward_list>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <optional>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using lint = long long;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(nullptr), ios::sync_with_stdio(false), cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template <typename T> bool chmax(T &m, const T q) { return m < q ? (m = q, true) : false; }
template <typename T> bool chmin(T &m, const T q) { return m > q ? (m = q, true) : false; }
const std::vector<std::pair<int, int>> grid_dxs{{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
int floor_lg(long long x) { return x <= 0 ? -1 : 63 - __builtin_clzll(x); }
template <class T1, class T2> T1 floor_div(T1 num, T2 den) { return (num > 0 ? num / den : -((-num + den - 1) / den)); }
template <class T1, class T2> std::pair<T1, T2> operator+(const std::pair<T1, T2> &l, const std::pair<T1, T2> &r) { return std::make_pair(l.first + r.first, l.second + r.second); }
template <class T1, class T2> std::pair<T1, T2> operator-(const std::pair<T1, T2> &l, const std::pair<T1, T2> &r) { return std::make_pair(l.first - r.first, l.second - r.second); }
template <class T> std::vector<T> sort_unique(std::vector<T> vec) { sort(vec.begin(), vec.end()), vec.erase(unique(vec.begin(), vec.end()), vec.end()); return vec; }
template <class T> int arglb(const std::vector<T> &v, const T &x) { return std::distance(v.begin(), std::lower_bound(v.begin(), v.end(), x)); }
template <class T> int argub(const std::vector<T> &v, const T &x) { return std::distance(v.begin(), std::upper_bound(v.begin(), v.end(), x)); }
template <class IStream, class T> IStream &operator>>(IStream &is, std::vector<T> &vec) { for (auto &v : vec) is >> v; return is; }

template <class OStream, class T> OStream &operator<<(OStream &os, const std::vector<T> &vec);
template <class OStream, class T, size_t sz> OStream &operator<<(OStream &os, const std::array<T, sz> &arr);
template <class OStream, class T, class TH> OStream &operator<<(OStream &os, const std::unordered_set<T, TH> &vec);
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const pair<T, U> &pa);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::deque<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::set<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::multiset<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::unordered_multiset<T> &vec);
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const std::pair<T, U> &pa);
template <class OStream, class TK, class TV> OStream &operator<<(OStream &os, const std::map<TK, TV> &mp);
template <class OStream, class TK, class TV, class TH> OStream &operator<<(OStream &os, const std::unordered_map<TK, TV, TH> &mp);
template <class OStream, class... T> OStream &operator<<(OStream &os, const std::tuple<T...> &tpl);

template <class OStream, class T> OStream &operator<<(OStream &os, const std::vector<T> &vec) { os << '['; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <class OStream, class T, size_t sz> OStream &operator<<(OStream &os, const std::array<T, sz> &arr) { os << '['; for (auto v : arr) os << v << ','; os << ']'; return os; }
template <class... T> std::istream &operator>>(std::istream &is, std::tuple<T...> &tpl) { std::apply([&is](auto &&... args) { ((is >> args), ...);}, tpl); return is; }
template <class OStream, class... T> OStream &operator<<(OStream &os, const std::tuple<T...> &tpl) { os << '('; std::apply([&os](auto &&... args) { ((os << args << ','), ...);}, tpl); return os << ')'; }
template <class OStream, class T, class TH> OStream &operator<<(OStream &os, const std::unordered_set<T, TH> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::deque<T> &vec) { os << "deq["; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::unordered_multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const std::pair<T, U> &pa) { return os << '(' << pa.first << ',' << pa.second << ')'; }
template <class OStream, class TK, class TV> OStream &operator<<(OStream &os, const std::map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
template <class OStream, class TK, class TV, class TH> OStream &operator<<(OStream &os, const std::unordered_map<TK, TV, TH> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
#ifdef HITONANODE_LOCAL
const string COLOR_RESET = "\033[0m", BRIGHT_CYAN = "\033[1;36m", NORMAL_FAINT = "\033[0;2m";
#define dbg(x) std::cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << std::endl
#define dbgif(cond, x) ((cond) ? std::cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << std::endl : std::cerr)
#else
#define dbg(x) ((void)0)
#define dbgif(cond, x) ((void)0)
#endif

// https://hitonanode.github.io/cplib-cpp/flow/maxflow_pushrelabel.hpp
#include <cassert>
#include <limits>
#include <utility>
#include <vector>

// Maxflow (push-relabel, highest-label)
// Complexity: O(N^2 M^(1/2))
template <class Cap, int GlobalRelabelFreq = 5, bool UseGapRelabeling = true>
struct mf_pushrelabel {
    struct pque_ {
        std::vector<std::pair<int, int>> even_, odd_;
        int se, so;
        void init(int n) { even_.resize(n), odd_.resize(n), se = so = 0; };
        void clear() { se = so = 0; }
        bool empty() const { return se + so == 0; }
        void push(int i, int h) { (h & 1 ? odd_[so++] : even_[se++]) = {i, h}; }
        int highest() const {
            int a = se ? even_[se - 1].second : -1, b = so ? odd_[so - 1].second : -1;
            return a > b ? a : b;
        }
        int pop() {
            if (!se or (so and odd_[so - 1].second > even_[se - 1].second))
                return odd_[--so].first;
            return even_[--se].first;
        }
    } pque;
    int _n;
    struct _edge {
        int to, rev;
        Cap cap;
    };
    std::vector<std::vector<_edge>> g;
    std::vector<std::pair<int, int>> pos;
    mf_pushrelabel(int n) : _n(n), g(n) {
        static_assert(GlobalRelabelFreq >= 0, "Global relabel parameter must be nonnegative.");
    }
    int add_edge(int from, int to, Cap cap) {
        assert(0 <= from and from < _n);
        assert(0 <= to and to < _n);
        assert(0 <= cap);
        int m = int(pos.size());
        pos.emplace_back(from, int(g[from].size()));
        int from_id = g[from].size(), to_id = g[to].size() + (from == to);
        g[from].push_back({to, to_id, cap});
        g[to].push_back({from, from_id, Cap(0)});
        return m;
    }

    struct edge {
        int from, to;
        Cap cap, flow;
    };

    edge get_edge(int i) const {
        int m = int(pos.size());
        assert(0 <= i and i < m);
        auto e = g[pos[i].first][pos[i].second], re = g[e.to][e.rev];
        return edge{pos[i].first, e.to, e.cap + re.cap, re.cap};
    }
    std::vector<edge> edges() const {
        std::vector<edge> ret(pos.size());
        for (int i = 0; i < int(pos.size()); i++) ret[i] = get_edge(i);
        return ret;
    }

    std::vector<int> dist;
    std::vector<int> dcnt;
    std::vector<Cap> excess;
    int gap;
    void global_relabeling(int t) {
        dist.assign(_n, _n), dist[t] = 0;
        static std::vector<int> q;
        if (q.empty()) q.resize(_n);
        q[0] = t;
        int qb = 0, qe = 1;
        pque.clear();
        if (UseGapRelabeling) gap = 1, dcnt.assign(_n + 1, 0);

        while (qb < qe) {
            int now = q[qb++];
            if (UseGapRelabeling) gap = dist[now] + 1, dcnt[dist[now]]++;
            if (excess[now] > 0) pque.push(now, dist[now]);
            for (const auto &e : g[now]) {
                if (g[e.to][e.rev].cap and dist[e.to] == _n) {
                    dist[e.to] = dist[now] + 1;
                    while (int(q.size()) <= qe) q.push_back(0);
                    q[qe++] = e.to;
                }
            }
        }
    }
    Cap flow(int s, int t) { return flow(s, t, std::numeric_limits<Cap>::max(), true); }
    Cap flow(int s, int t, Cap flow_limit, bool retrieve = true) {
        assert(0 <= s and s < _n);
        assert(0 <= t and t < _n);
        assert(s != t);
        excess.resize(_n, 0);
        excess[s] += flow_limit, excess[t] -= flow_limit;
        dist.assign(_n, 0);
        dist[s] = _n;
        if (UseGapRelabeling) gap = 1, dcnt.assign(_n + 1, 0), dcnt[0] = _n - 1;
        pque.init(_n);
        for (auto &e : g[s]) _push(s, e);
        _run(t);
        Cap ret = excess[t] + flow_limit;
        excess[s] += excess[t], excess[t] = 0;
        if (retrieve) {
            global_relabeling(s);
            _run(s);
            assert(excess == std::vector<Cap>(_n, 0));
        }
        return ret;
    }
    void _run(int t) {
        if (GlobalRelabelFreq) global_relabeling(t);
        int tick = pos.size() * GlobalRelabelFreq;
        while (!pque.empty()) {
            int i = pque.pop();
            if (UseGapRelabeling and dist[i] > gap) continue;
            int dnxt = _n * 2 - 1;
            for (auto &e : g[i]) {
                if (!e.cap) continue;
                if (dist[e.to] == dist[i] - 1) {
                    _push(i, e);
                    if (excess[i] == 0) break;
                } else {
                    if (dist[e.to] + 1 < dnxt) dnxt = dist[e.to] + 1;
                }
            }
            if (excess[i] > 0) {
                if (UseGapRelabeling) {
                    if (dnxt != dist[i] and dcnt[dist[i]] == 1 and dist[i] < gap) gap = dist[i];
                    if (dnxt == gap) gap++;
                    while (pque.highest() > gap) pque.pop();
                    if (dnxt > gap) dnxt = _n;
                    if (dist[i] != dnxt) dcnt[dist[i]]--, dcnt[dnxt]++;
                }
                dist[i] = dnxt;
                if (!UseGapRelabeling or dist[i] < gap) pque.push(i, dist[i]);
            }
            if (GlobalRelabelFreq and --tick == 0) {
                tick = pos.size() * GlobalRelabelFreq, global_relabeling(t);
            }
        }
        return;
    }

    void _push(int i, _edge &e) {
        Cap delta = e.cap < excess[i] ? e.cap : excess[i];
        excess[i] -= delta, e.cap -= delta;
        excess[e.to] += delta, g[e.to][e.rev].cap += delta;
        if (excess[e.to] > 0 and excess[e.to] <= delta) {
            if (!UseGapRelabeling or dist[e.to] <= gap) pque.push(e.to, dist[e.to]);
        }
    }
};


int main() {
    int N, M, S, T;
    cin >> N >> M >> S >> T;

    mf_pushrelabel<lint> mf(N);
    REP(_, M) {
        int u, v, c;
        cin >> u >> v >> c;
        --u, --v;
        mf.add_edge(u, v, c);
    }

    --S, --T;
    cout << mf.flow(S, T) << '\n';
}