#include <iostream>
#include <algorithm>

using namespace std;

const int N = 1010, M = 1010;
int n, m;
char a[N], b[M]; // 这里是char，不是int
int f[N][N];

int main () {
    cin >> n >> m;
    scanf("%s%s", a + 1, b + 1); //因为使用了f[i-1][j-1]所以下标从1开始a+1,b+1

    for (int i = 1; i <= n; i ++) 
        for (int j = 1; j <= m; j ++) {
            f[i][j] = max(f[i - 1][j], f[i][j - 1]); //必须先执行，不可放在if()后面再执行
            if (a[i] ==  b[j])
                f[i][j] = max(f[i][j], f[i - 1][j - 1] + 1);
        }

    cout << f[n][m] << endl;
    return 0;
}