#include <bits/stdc++.h>

typedef long double ld;
typedef long long ll;
using namespace std;
int di[] = {1, 0, -1, 0, -1, 1, -1, 1};
int dj[] = {0, 1, 0, -1, -1, 1, 1, -1};
const ll oo = 1e18, MOD = 998244353;
const int N = 2e5 + 5, M = 1e6 + 5;
const ld PI = acos(-1.0), EPS = 1e-9;

//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//using namespace __gnu_pbds;
//typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

int n, m, dp1[N][2], dp2[N][2][2], vis[N];
vector<int> v1[N], v2[N], v;

int solve1(int node, int par, int num) {
    int &ret = dp1[node][num];
    if (~ret) return ret;
    if (v1[node].size() == 1 && node >= n) return dp1[node][num] = 0;
    if (v1[node].empty()) return dp1[node][num] = 0;
    ret = 0;
    for (auto x:v1[node]) {
        if (x != par && x >= n) {
            int tmp = 1 + solve1(x, node, 1);
            if (num) tmp = min(tmp, solve1(x, node, 0));
            ret += tmp;
        }
    }
    return ret;
}

void dfs(int node) {
    vis[node] = 1;
    v.push_back(node);
    for (auto x:v2[node]) {
        if (!vis[x]) dfs(x);
    }
}

int solve2(int idx, int pre, int lst) {
    int &ret = dp2[idx][pre][lst];
    if (~ret) return ret;
    ret = 1e9;
    if (idx == v.size() - 1) {
        ret = min(ret, solve1(v[idx], v[idx], 1));
        if (pre && lst) ret = min(ret, solve1(v[idx], v[idx], 0));
            //cout<<idx<<" "<<pre<<" "<<ret<<" "<<lst<<endl;

        return ret;
    }
    ret = min(ret, solve1(v[idx], v[idx], 1) + solve2(idx + 1, 1, lst));
    if (pre) ret = min(ret, solve1(v[idx], v[idx], 0) + solve2(idx + 1, 0, lst));
    //cout<<idx<<" "<<pre<<" "<<ret<<" "<<lst<<endl;
    return ret;
}

//#define endl '\n'
int main() {
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    //freopen("farm.in", "r", stdin);
    memset(dp1, -1, sizeof dp1);
    memset(dp2, -1, sizeof dp2);
    cin >> n >> m;
    for (int i = 1; i <= n + m; i++) {
        int x, y;
        cin >> x >> y;
        if (x < n && y < n) {
            v2[x].push_back(y);
            v2[y].push_back(x);
        } else {
            v1[x].push_back(y);
            v1[y].push_back(x);
        }
    }
    for (int i = 0; i < n; i++) {
        solve1(i, i, 0);
        solve1(i, i, 1);
        dp1[i][1]++;
        //swap(dp1[i][0], dp1[i][1]);
        //cout<<i<<" "<<dp1[i][0]<<" "<<dp1[i][1]<<endl;
    }
    dfs(0);
    int c1 = solve2(1, 0, 0) + dp1[v[0]][0];
    int c2 = solve2(1, 1, 1) + dp1[v[0]][1];
    //cout<<solve1(5,5,1)<<endl;
    cout << min(c1, c2);
    return 0;
}