#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
#define r(a, b, c, r, ...) r
#define r2(i, a, b) for(ll i = ll(a); i < ll(b); ++i)
#define r1(i, b) r2(i, 0, b)
#define rep(...) r(__VA_ARGS__, r2, r1)(__VA_ARGS__)
const ll INF = 1ll << 60;  // 1e18
const ll MOD = 1000000007;

int main() {
    {
        ll n;
        cin >> n;
        cin >> n;
    }
    string s, t;
    cin >> s >> t;
    vector<vll> d(s.size() + 1, vll(t.size() + 1, INF));
    d[0][0] = 0;
    rep(i, -1, s.size()) rep(j, -1, t.size()) {
        if(i != -1 && j != -1) {
            if(s[i] == t[j]) d[i + 1][j + 1] = min(d[i + 1][j + 1], d[i][j]);
            else
                d[i + 1][j + 1] = min(d[i + 1][j + 1], d[i][j] + 1);
        }
        if(i != -1) d[i + 1][j + 1] = min(d[i + 1][j + 1], d[i][j + 1] + 1);  // del
        if(j != -1) d[i + 1][j + 1] = min(d[i + 1][j + 1], d[i + 1][j] + 1);  // insert
    }
    cout << d[s.size()][t.size()] << endl;
}