#include <bits/stdc++.h>

using namespace std;

int n, m;
char a[1010], b[1010];
int f[1010][1010];

int main(void) {
    cin >> n >> m >> 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]);
            if (a[i] == b[j]) f[i][j] = max(f[i][j], f[i - 1][j - 1] + 1);
        }

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

}