#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1010;
int n, m;
char a[N], b[N];
int f[N][N];
int main()
{
scanf("%d%d", &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]); //即使当前元素不相等,也能存下上一个相等的最长子序列
if (a[i] == b[j]) f[i][j] = max(f[i][j], f[i - 1][j - 1] + 1);
}
printf("%d\n", f[n][m]);
return 0;
}