#include <iostream>
using namespace std;
const int N = 1010;
int f[N][N];
int main(){
int alen, blen;
cin >> alen >> blen;
string a, b;
cin >> a >> b;
a = " " + a;
b = " " + b;
for(int i = 1; i <= alen; i ++ ){
for(int j = 1; j <= blen; j ++ ){
if(a[i] == b[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[alen][blen] << endl;
return 0;
}