#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1010;
int n, m;
char a[N], b[N];
int f[N][N];
int main() {
    scanf("%d%d", &n, &m);
    scanf("%s%s", 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]);//看一下第i和第j个字母有没有出现
            //i-1，j-1 是包含在上面两种情况中的
            if (a[i] == b[j]) f[i][j] = max(f[i][j], f[i - 1][j - 1] + 1);
        }
    printf("%d\n", f[n][m]);
    return 0;
}