#define _USE_MATH_DEFINES
#pragma region include
#include <iostream>
#include <iomanip>
#include <stdio.h>

#include <sstream>
#include <algorithm>
#include <iterator>
#include <cmath>
#include <complex>

#include <string>
#include <cstring>
#include <vector>
#include <bitset>

#include <queue>
#include <set>
#include <map>
#include <stack>
#include <list>

#include <ctime>
////
//#include <random>//
#pragma endregion //#include
/////////

#pragma region typedef
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
#pragma endregion //typedef
////定数
const int INF = (int)1e9;
const LL MOD = (LL)1e9+7;
const LL LINF = (LL)4e18+20;
const LD PI = acos(-1.0);
const double EPS = 1e-9;
/////////
using namespace::std;

void solve(){
	int R,C;
	cin>>R>>C;
	vector<vector<int> > fld(R,vector<int>(C));
	for(int r=0;r<R;++r){
		for(int c=0;c<C;++c){
			cin>>fld[r][c];
			if(fld[r][c]){
				fld[r][c] = -1;
			}
		}
	}
	int count = 0;
	vector<bool> use(R*C+1,false);
	for(int r=0;r<R;++r){
		for(int c=0;c<C;++c){
			int color = fld[r][c];
			if(color == 0){
				continue;
			}
			if(color == -1 ){
				++count;
				color = count;
				use[color] = true;
			}else{
				//colorに値が入っている。
			}
			if(r+1<R){
				int aite = fld[r+1][c];
				
				if( aite == -1 ){
					fld[r+1][c] = color;
				}else if(aite >0 && color != aite){//既に縫ってある。
					use[ max(color,aite) ] = false;
				}
			}
			if(c+1<C){
				int aite = fld[r][c+1];
				if(aite==-1){
					fld[r][c+1] = color;
				}else if(aite>0 && color != aite){
					use[ max(color,aite) ] = false;
				}
			}
		}
	}
	
	int ans = 0;
	for(int i=1;i<=R*C;++i){
		if(use[i]){
			++ans;
		}
	}
	cout << ans << endl;
}

#pragma region main
signed main(void){
	std::cin.tie(0);
	std::ios::sync_with_stdio(false);
	std::cout << std::fixed;//小数を10進数表示
	cout << setprecision(16);//小数点以下の桁数を指定//coutとcerrで別	

	solve();
}
#pragma endregion //main()