#include <iostream>
#include <cstring>

using namespace std;

const int N = 1010;

int n, m;
char a[N], b[N];
int f[N][N];

int main(){
    scanf("%d%s", &n, a + 1);
    scanf("%d%s", &m, b + 1);

    for (int i = 0; i <= m; i ++ ) f[0][i] = i;//a用0个字母，和b匹配只能进行添加的操作
    for (int i = 0; i <= n; i ++ ) f[i][0] = i;//初始化f[i][0]，用a的前i个字母和b的第0个字符匹配

    for (int i = 1; i <= n; i ++ )
        for (int j = 1; j <= m; j ++ ){
            f[i][j] = min(f[i - 1][j] + 1, f[i][j - 1] + 1);//删和增
            if (a[i] == b[j]) f[i][j] = min(f[i][j], f[i - 1][j - 1]);//如果当前相等，就不需要操作
            else f[i][j] = min(f[i][j], f[i - 1][j - 1] + 1);//如果不相等，就给他换字符（a与b前i-1个字符相同
        }

    printf("%d\n", f[n][m]);

    return 0;
}