RAOCAY C++

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

const int N = 1010;

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

int n, m, a[N][N];
bool can(int x, int y) {
  return (x >= 0 && y >= 0 && x < n && y < m && a[x][y]);
}


int dem(int x, int y) {
  int res = 0;
  for (int i = 0; i < 4; i++) {
    int u = x + dx[i], v = y + dy[i];
    if (!can(u, v)) {
      res++;
    }
  }
  return res;
}

int main() {
  freopen("RAOCAY.INP", "r", stdin);
  freopen("RAOCAY.OUT", "w", stdout);
  scanf("%d %d", &n, &m);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      scanf("%d", &a[i][j]);
    }
  }
  int res = 0;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (a[i][j] ==1){
        res += dem(i, j);
      }
    }
  }
  printf("%d\n", res);
  return 0;
}