#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
const int N = 1010;
int f[N][N]; // f[i][j] 表示s1前i个字符和 s2前j个字符公共子序列的最大值
char s1[N], s2[N];
int main()
{
    int m,n;
    cin >> m >> n; // 字符串的长度
    cin >> s1+1 >> s2+1;
    f[1][0] = f[0][1] = 0;
    for(int i = 1;i <= m;i++)
    {
        for(int j = 1; j <= n;j++)
        {
            if(s1[i] == s2[j])  f[i][j] = f[i-1][j-1]+1;
            else f[i][j] = max(f[i-1][j],f[i][j-1]);
        }
    }
    cout << f[m][n];
    return 0;
}