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const int MAXN = ...; // число вершин
const int INF = 1000000000; // константа-бесконечность
 
struct edge {
	int a, b, cap, flow;
};
 
int n, s, t, d[MAXN], ptr[MAXN], q[MAXN];
vector<edge> e;
vector<int> g[MAXN];
 
void add_edge (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);
}
 
bool bfs() {
	int qh=0, qt=0;
	q[qt++] = s;
	memset (d, -1, n * sizeof d[0]);
	d[s] = 0;
	while (qh < qt && d[t] == -1) {
		int v = q[qh++];
		for (size_t i=0; i<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;
}
 
int dinic() {
	int flow = 0;
	for (;;) {
		if (!bfs())  break;
		memset (ptr, 0, n * sizeof ptr[0]);
		while (int pushed = dfs (s, INF))
			flow += pushed;
	}
	return flow;
}

prog.cpp:1:18: error: expected primary-expression before ‘...’ token
 const int MAXN = ...; // число вершин
                  ^~~
prog.cpp:8:20: error: size of array ‘d’ is not an integral constant-expression
 int n, s, t, d[MAXN], ptr[MAXN], q[MAXN];
                    ^
prog.cpp:8:31: error: size of array ‘ptr’ is not an integral constant-expression
 int n, s, t, d[MAXN], ptr[MAXN], q[MAXN];
                               ^
prog.cpp:8:40: error: size of array ‘q’ is not an integral constant-expression
 int n, s, t, d[MAXN], ptr[MAXN], q[MAXN];
                                        ^
prog.cpp:9:1: error: ‘vector’ does not name a type
 vector<edge> e;
 ^~~~~~
prog.cpp:10:1: error: ‘vector’ does not name a type
 vector<int> g[MAXN];
 ^~~~~~
prog.cpp: In function ‘void add_edge(int, int, int)’:
prog.cpp:15:2: error: ‘g’ was not declared in this scope
  g[a].push_back ((int) e.size());
  ^
prog.cpp:15:24: error: ‘e’ was not declared in this scope
  g[a].push_back ((int) e.size());
                        ^
prog.cpp: In function ‘bool bfs()’:
prog.cpp:24:32: error: ‘memset’ was not declared in this scope
  memset (d, -1, n * sizeof d[0]);
                                ^
prog.cpp:28:8: error: ‘size_t’ was not declared in this scope
   for (size_t i=0; i<g[v].size(); ++i) {
        ^~~~~~
prog.cpp:28:20: error: ‘i’ was not declared in this scope
   for (size_t i=0; i<g[v].size(); ++i) {
                    ^
prog.cpp:28:22: error: ‘g’ was not declared in this scope
   for (size_t i=0; i<g[v].size(); ++i) {
                      ^
prog.cpp:31:10: error: ‘to’ was not declared in this scope
    if (d[to] == -1 && e[id].flow < e[id].cap) {
          ^~
prog.cpp:31:23: error: ‘e’ was not declared in this scope
    if (d[to] == -1 && e[id].flow < e[id].cap) {
                       ^
prog.cpp: In function ‘int dfs(int, int)’:
prog.cpp:43:21: error: ‘g’ was not declared in this scope
  for (; ptr[v]<(int)g[v].size(); ++ptr[v]) {
                     ^
prog.cpp:46:9: error: ‘to’ was not declared in this scope
   if (d[to] != d[v] + 1)  continue;
         ^~
prog.cpp:47:21: error: ‘to’ was not declared in this scope
   int pushed = dfs (to, min (flow, e[id].cap - e[id].flow));
                     ^~
prog.cpp:47:36: error: ‘e’ was not declared in this scope
   int pushed = dfs (to, min (flow, e[id].cap - e[id].flow));
                                    ^
prog.cpp:47:58: error: ‘min’ was not declared in this scope
   int pushed = dfs (to, min (flow, e[id].cap - e[id].flow));
                                                          ^
prog.cpp: In function ‘int dinic()’:
prog.cpp:61:36: error: ‘memset’ was not declared in this scope
   memset (ptr, 0, n * sizeof ptr[0]);
                                    ^

Standard output is empty