#include<iostream>
using namespace std;
const int N = 1010;
int n,m;
int f[N][N];
char a[N], b[N];
int main()
{
    cin >> 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]);
            if(a[i] == b[j])
                f[i][j] = max(f[i][j], f[i - 1][j - 1] + 1);
        }
    cout << f[n][m];
    return 0;
}