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

#define rep(i,a,b) for(int i=a;i<b;++i)
#define all(x) begin(x),end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
const int MAXN = 2e5+5;
vector<int>adj[MAXN];
ll dp[2][MAXN],n,m;
void dfs(int v,int u){
    dp[0][v] = 0;
    dp[1][v] = 1;
    for(int x:adj[v]){
        if(x == u || x<n)continue;
        dfs(x,v);
        dp[0][v] += dp[1][x];
        dp[1][v] += min(dp[0][x],dp[1][x]);
    }
}
ll p[3][MAXN];
void run(int n){
    for(int i=1;i<n;i++){
        p[0][i] = p[1][i-1] + dp[0][i];
        p[1][i] = min(p[1][i-1],p[0][i-1]) + dp[1][i];
    }

}
int main()
{
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    cin>>n>>m;
    for(int i=0;i<n+m;i++){
        int v,u;
        cin>>v>>u;
        adj[v].push_back(u);
        adj[u].push_back(v);
    }
    ll ans = n+m;
    for(int i=0;i<n;i++)dfs(i,-1);
    //for(int i=0;i<n+m;i++)cout<<dp[0][i]<<" "<<dp[1][i]<<" "<<dp[2][i]<<'\n';

    //node 0 is black
    for(int i=0;i<n;i++)p[0][i] = p[1][i] =  1e15;
    p[1][0] = dp[1][0];
    run(n);
    ans = min({ans,p[0][n-1],p[1][n-1]});

    p[1][1] = dp[0][0] + dp[1][1];
    for(int i=2;i<n;i++){
        p[0][i] = p[1][i-1] + dp[0][i];
        p[1][i] = min(p[1][i-1],p[0][i-1]) + dp[1][i];
    }
    ans = min({ans,p[1][n-1]});
    cout<<ans<<'\n';




}