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

const int N=1005;
int f[N][N];
int n, m;

int main(){
    string a, b;
    cin>>n;
    cin>>a;
    cin>>m;
    cin>>b;
    memset(f, 0x00, sizeof f);
    for(register int i=1; i<=m; ++i) f[0][i]=i; // only insert for string a
    for(register int j=1; j<=n; ++j) f[j][0]=j; // only delete for string a
    for(int i=1; i<=n; ++i)
        for(int j=1; j<=m; ++j){
            // op: Delete & Update & Insert
            f[i][j]=min(f[i-1][j], min(f[i][j-1], f[i-1][j-1]))+1;
            if(a[i-1]==b[j-1]) f[i][j]=min(f[i][j], f[i-1][j-1]);
        }
    cout<<f[n][m]<<endl;

    return 0;
}