struct Edge {
int a, b, cap, flow;
};
struct MaxFlow {
int n, s, t;
vector<int> d, ptr, q;
vector< Edge > e;
vector< vector<int> > g;
MaxFlow(int _n) : n(_n), d(_n), ptr(_n), q(_n), g(_n) {
e.clear();
for (int i = 0; i < n; i++) {
g[i].clear();
ptr[i] = 0;
}
}
void addEdge(int a, int b, int cap) {
Edge e1 = { a, b, cap, 0 };
Edge e2 = { b, a, 0, 0 };
g[a].push_back( (int) e.size() );
e.push_back(e1);
g[b].push_back( (int) e.size() );
e.push_back(e2);
}
int getMaxFlow(int _s, int _t) {
s = _s; t = _t;
int flow = 0;
for (;;) {
if (!bfs()) break;
std::fill(ptr.begin(), ptr.end(), 0);
while (int pushed = dfs(s, inf))
flow += pushed;
}
return flow;
}
private:
bool bfs() {
int qh = 0, qt = 0;
q[qt++] = s;
std::fill(d.begin(), d.end(), -1);
d[s] = 0;
while (qh < qt && d[t] == -1) {
int v = q[qh++];
for (int i = 0; i < (int) g[v].size(); i++) {
int id = g[v][i], to = e[id].b;
if (d[to] == -1 && e[id].flow < e[id].cap) {
q[qt++] = to;
d[to] = d[v] + 1;
}
}
}
return d[t] != -1;
}
int dfs (int v, int flow) {
if (!flow) return 0;
if (v == t) return flow;
for (; ptr[v] < (int)g[v].size(); ++ptr[v]) {
int id = g[v][ptr[v]],
to = e[id].b;
if (d[to] != d[v] + 1) continue;
int pushed = dfs(to, min(flow, e[id].cap - e[id].flow));
if (pushed) {
e[id].flow += pushed;
e[id^1].flow -= pushed;
return pushed;
}
}
return 0;
}
};
struct FlowEdge {
int v, u;
long long cap, flow = 0;
FlowEdge(int v, int u, long long cap) : v(v), u(u), cap(cap) {}
};
struct Dinic {
const long long flow_inf = 1e18;
vector<FlowEdge> edges;
vector<vector<int>> adj;
int n, m = 0;
int s, t;
vector<int> level, ptr;
queue<int> q;
Dinic(int n, int s, int t) : n(n), s(s), t(t) {
adj.resize(n);
level.resize(n);
ptr.resize(n);
}
void addEdge(int v, int u, long long cap) {
edges.emplace_back(v, u, cap);
edges.emplace_back(u, v, 0);
adj[v].push_back(m);
adj[u].push_back(m + 1);
m += 2;
}
bool bfs() {
while (!q.empty()) {
int v = q.front();
q.pop();
for (int id : adj[v]) {
if (edges[id].cap == edges[id].flow)
continue;
if (level[edges[id].u] != -1)
continue;
level[edges[id].u] = level[v] + 1;
q.push(edges[id].u);
}
}
return level[t] != -1;
}
long long dfs(int v, long long pushed) {
if (pushed == 0)
return 0;
if (v == t)
return pushed;
for (int& cid = ptr[v]; cid < (int)adj[v].size(); cid++) {
int id = adj[v][cid];
int u = edges[id].u;
if (level[v] + 1 != level[u])
continue;
long long tr = dfs(u, min(pushed, edges[id].cap - edges[id].flow));
if (tr == 0)
continue;
edges[id].flow += tr;
edges[id ^ 1].flow -= tr;
return tr;
}
return 0;
}
long long getMaxFlow() {
long long f = 0;
while (true) {
fill(level.begin(), level.end(), -1);
level[s] = 0;
q.push(s);
if (!bfs())
break;
fill(ptr.begin(), ptr.end(), 0);
while (long long pushed = dfs(s, flow_inf)) {
f += pushed;
}
}
return f;
}
};