#include<iostream>
#include<algorithm>
using namespace std;
const int MAX = 1010;
int m, n;
char a[MAX], b[MAX];
int f[MAX][MAX];
int main()
{
scanf("%d %d", &m, &n);
scanf("%s%s", a + 1, b + 1);
for (int i = 1; i <= m; i ++)
for (int j = 1; j <= n; 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[m][n];
return 0;
}