// #牛客春招刷题训练营# https://www.nowcoder.com/discuss/726480854079250432
// 思路是区间dp;
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
int main() {
int n, m;
cin >> n >> m;
string sn, sm;
cin >> sn >> sm;
vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));//--------dp[i][j]表示只考虑sn的前i个字符和sm的前j个字符时的最长公共子区间
for (int i = 1; i <= n; i++){
for (int j = 1; j <= m; j++){
if (sn[i - 1] == sm[j - 1]) dp[i][j] = dp[i - 1][j - 1] + 1;//--------如果sn[i]与sm[j]相等,....,dp[i - 1][j - 1]是没有考虑sn[i], sm[j]的所以用它加
else dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
}
}
cout << dp[n][m];
}
// 64 位输出请用 printf("%lld")