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struct Edge {
int to, rev;
ll f, c;
};
vector<vector<Edge>> adj;
vector<vector<int>> hs;
vector<ll> ec;
vector<int> cur, H;
void addEdge(int u, int v, ll c) {
adj[u].push_back({v, (int)ssize(adj[v]), 0, c});
adj[v].push_back({u, (int)ssize(adj[u])-1, 0, 0});
}
void addFlow(Edge& e, ll f) {
if (ec[e.to] == 0 && f > 0)
hs[H[e.to]].push_back(e.to);
e.f += f;
adj[e.to][e.rev].f -= f;
ec[e.to] += f;
ec[adj[e.to][e.rev].to] -= f;
}
ll maxFlow(int s, int t) {
int n = ssize(adj);
hs.assign(2*n, {});
ec.assign(n, 0);
cur.assign(n, 0);
H.assign(n, 0);
H[s] = n;
ec[t] = 1; //never set t to active...
vector<int> co(2*n);
co[0] = n - 1;
for (Edge& e : adj[s]) addFlow(e, e.c);
for (int hi = 0;;) {
while (hs[hi].empty()) if (!hi--) return -ec[s];
int v = hs[hi].back();
hs[hi].pop_back();
while (ec[v] > 0) {
if (cur[v] == ssize(adj[v])) {
H[v] = 2*n;
for (int i = 0; i < ssize(adj[v]); i++) {
Edge& e = adj[v][i];
if (e.c - e.f > 0 &&
H[v] > H[e.to] + 1) {
H[v] = H[e.to] + 1;
cur[v] = i;
}}
co[H[v]]++;
if (!--co[hi] && hi < n) {
for (int i = 0; i < n; i++) {
if (hi < H[i] && H[i] < n) {
co[H[i]]--;
H[i] = n + 1;
}}}
hi = H[v];
} else {
Edge& e = adj[v][cur[v]];
if (e.c - e.f > 0 && H[v] == H[e.to] + 1) {
addFlow(adj[v][cur[v]], min(ec[v], e.c - e.f));
} else {
cur[v]++;
}}}}}
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