#include<bits/stdc++.h>
using namespace std;

const int N=1e3;

int f[1001][1001];
int main() {
    int n,m;
 char a[1001], b[1001];
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] =  f[i - 1][j - 1] + 1;
         }
     }
     cout << f[n][m] << endl;
    return 0;
}