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

#define ALL(obj) (obj).begin(),(obj).end()
template<class T> using priority_queue_reverse = priority_queue<T,vector<T>,greater<T>>;

constexpr long long MOD = 1'000'000'000LL + 7; //'
constexpr long long MOD2 = 998244353;
constexpr long long HIGHINF = (long long)1e18;
constexpr long long LOWINF = (long long)1e15;
constexpr long double PI = 3.1415926535897932384626433L;

template <class T> vector<T> multivector(size_t N,T init){return vector<T>(N,init);}
template <class... T> auto multivector(size_t N,T... t){return vector<decltype(multivector(t...))>(N,multivector(t...));}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; exit(0);}}
template <class T, class U>ostream &operator<<(ostream &o, const map<T, U>&obj) {o << "{"; for (auto &x : obj) o << " {" << x.first << " : " << x.second << "}" << ","; o << " }"; return o;}
template <class T>ostream &operator<<(ostream &o, const set<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const multiset<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const vector<T>&obj) {o << "{"; for (int i = 0; i < (int)obj.size(); ++i)o << (i > 0 ? ", " : "") << obj[i]; o << "}"; return o;}
template <class T, class U>ostream &operator<<(ostream &o, const pair<T, U>&obj) {o << "{" << obj.first << ", " << obj.second << "}"; return o;}
void print(void) {cout << endl;}
template <class Head> void print(Head&& head) {cout << head;print();}
template <class Head, class... Tail> void print(Head&& head, Tail&&... tail) {cout << head << " ";print(forward<Tail>(tail)...);}
template <class T> void chmax(T& a, const T b){a=max(a,b);}
template <class T> void chmin(T& a, const T b){a=min(a,b);}
vector<string> split(const string &str, const char delemiter) {vector<string> res;stringstream ss(str);string buffer; while( getline(ss, buffer, delemiter) ) res.push_back(buffer); return res;}
int msb(int x) {return x?31-__builtin_clz(x):-1;}
void YN(bool flg) {cout << (flg ? "YES" : "NO") << endl;}
void Yn(bool flg) {cout << (flg ? "Yes" : "No") << endl;}
void yn(bool flg) {cout << (flg ? "yes" : "no") << endl;}

/**
 * @url 
 * @est
 */ 
int main() {
    cin.tie(0);ios::sync_with_stdio(false);
    int N,M; cin >> N >> M;
    vector<int> A(N+1),B(M+1);
    for(int i=1;i<=N;++i) cin >> A[i];
    for(int i=1;i<=M;++i) cin >> B[i];
    auto dp = multivector(N+1,M+1,2,123456789);
    dp[0][0][0]=0;
    for(int i=0;i<=N;++i) {
        for(int j=0;j<=M;++j) {
            if(i+1<=N && j+1<=M) {
                int flg = (A[i+1]!=B[j+1]);
                chmin(dp[i+1][j+1][flg],dp[i][j][0]+flg);
                chmin(dp[i+1][j+1][flg],dp[i][j][1]+flg);
            }
            if(i+1<=N) {
                int flg = (A[i+1]!=B[j]);
                chmin(dp[i+1][j][flg],dp[i][j][1]+flg);
                chmin(dp[i+1][j][0]  ,dp[i][j][0]+1);
            }
            if(j+1<=M) {
                int flg = (A[i]!=B[j+1]);
                chmin(dp[i][j+1][flg],dp[i][j][1]+flg);
                chmin(dp[i][j+1][0]  ,dp[i][j][0]+1);
            }
        }
    }
    cout << min(dp[N][M][0],dp[N][M][1]) << endl;
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define each(e, v) for(auto &e: v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const int MOD = 1000000007;
//const int MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

int main(){
    int N, M;
    cin >> N >> M;
    vector<int> A(N), B(M);
    rep(i, N) cin >> A[i];
    rep(i, M) cin >> B[i];

    vector<vector<int>> dp(N+1, vector<int>(M+1, inf));
    rep(i, N+1) dp[i][0] = i;
    rep(i, M+1) dp[0][i] = i;

    rep2(i, 1, N){
        rep2(j, 1, M){
            chmin(dp[i][j], dp[i-1][j]+1);
            chmin(dp[i][j], dp[i][j-1]+1);
            int x = (A[i-1] == B[j-1]);
            chmin(dp[i][j], dp[i-1][j-1]+1-x);
        }
    }

    cout << dp[N][M] << '\n';
}