#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1010, M = 1e6;

int n, m, res;
int p[N];
int ids[N][N];
int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};
int w[4] = {1, 1, 2, 2};

int find(int x){
    if(p[x] != x) p[x] = find(p[x]);
    return p[x];
}

void solve(){
    for(int k = 0;k < 4;k ++ )
        for(int i = 1;i <= n;i ++ )
            for(int j = 1;j <= m;j ++ ){
                int x = dx[k] + i, y = dy[k] + j;
                int a = ids[i][j], b = ids[x][y];
                a = find(a), b = find(b);
                if(a != b){
                    p[a] = b;
                    res += w[k];
                }
            }
}

int main(){

    cin >> n >> m;
    for(int i = 1,t = 1;i <= n;i ++ )
        for(int j = 1;j <= m;j ++ ,t ++ )
            ids[i][j] = t;

    for(int i = 1;i <= n * m;i ++ ) p[i] = i;

    int x1, y1, x2, y2;
    while(cin >> x1 >> y1 >> x2 >> y2){
        int a = ids[x1][y1], b = ids[x2][y2];
        p[find(a)] = find(b);
    }

    solve();

    cout << res << endl;

    return 0;
}