4WA 60tps

#include <bits/stdc++.h>
using namespace std;

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};

const int N = 1e7 + 10, M = 110, INF = 1e9;
int a[M][M];
int h[N], tmp[N], e[N], w[N], ne[N], idx;
int d[N];
int maxFlow;
int n, m;

int turn(int x, int y)
{
	return (x - 1) * m + y;
}

void add(int a, int b, int c)
{
	e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx++;
	e[idx] = a, w[idx] = 0, ne[idx] = h[b], h[b] = idx++;
}

bool bfs(int s, int T)
{
	for (int i = 0; i <= n * m + 1; i++) d[i] = -1;
	
	queue<int> q;
	
	q.push(s);
	d[s] = 0;
	
	while (q.size())
	{
		int t = q.front();
		q.pop();
		
		tmp[t] = h[t];
		
		for (int i = h[t]; ~i; i = ne[i])
		{
			int j = e[i];
			
			if (w[i] && d[j] == -1)
			{
				q.push(j);
				
				d[j] = d[t] + 1;
				
				if (j == T) return true;
			}
		}
	}
	
	return false;
}

int dinic(int u, int flow, int T)
{
	if (u == T) return flow;
	
	int left = flow;
	for (int i = tmp[u]; ~i; i = ne[i])
	{
		int j = e[i];
		
		tmp[u] = i;
		
		if (w[i] && d[j] == d[u] + 1)
		{
			int inc = dinic(j, min(left, w[i]), T);
			
			if (!inc) d[j] = -1;
			
			w[i] -= inc;
			w[i ^ 1] += inc;
			left -= inc;
		}
		
		if (!left) break;
	}
	
	return flow - left;
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);	
	
	cin >> n >> m;
	
	int s = 0, t = n * m + 1;
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++)
			cin >> a[i][j];
	
	for (int i = 0; i <= n * m * 5; i++) h[i] = -1;
	
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++)
			if (a[i][j] == 1)
				add(s, turn(i, j), INF);
		else if (a[i][j] == 2)
			add(turn(i, j), t, INF);
	
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++)
			for (int k = 0; k < 4; k++)
			{
				int a = i + dx[k], b = j + dy[k];
				
				if (a > 0 && a <= n && b > 0 && b <= m)
					add(turn(i, j), turn(a, b), 1);
			}
	
	int res = 0;
	while (bfs(s, t))
		res += dinic(s, INF, t);
	
	cout << res;
	
	
	return 0;
}