#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <cmath>
#include <algorithm>

using namespace std;

#define REP(i,n)	for(int i=0;i<(n);++i)
#define REPS(i,s,t)	for(int i=(s);i<(t);++i)
#define PER(i,n)	for(int i=0;i>(n);--i)
#define PERS(i,s,t)	for(int i=(s);i>(t);--i)

#define INF 		2000000007
#define MINF		-200000007
#define MOD			17 	
// 2^20

#define MAX 		200005

typedef unsigned int 			uint;
typedef unsigned long long int	ull;
typedef long long int 			ll;

template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
  for(T& x: vec) is >> x;
  //for(int i=0; i<vec.size(); i++) is >> x[i]; とかでもいいです。
  return is;
}

//int dp[MAX];
int H,W;
int cnt;
int dis;
void check(vector<vector<int> > &A,int y,int x){
	if(A[y][x]==0)return;
	int n = (y!=0) ? A[y-1][x] : 0;
	int w = (x!=0) ? A[y][x-1] : 0;
	if(n!=0&&w!=0){
		A[y][x] = min(n,w);
		if(n!=w)
			++dis;
	}
	else if(n==0&&w==0)
		A[y][x] = ++cnt;
	else
		A[y][x] = n+w;
}

int main(){
	cin>>H>>W;

	vector<vector<int> > A(H,vector<int>(W,false));
	cin>>A;

	REP(i,H)
		REP(j,W)
			check(A,i,j);
	cout << (cnt-dis) << endl;

	return 0;
}