#include <bits/stdc++.h>   using namespace std;   char s1[5010], s2[5010];   int dp[5010][5010];   int main() {     int i, j, ind, n, m, ans;     cin >> n >> m;     cin >> s1;     cin >> s2;     for (i = 1; i <= n; i++) {       for (j = 1; j <= m; j++) {         dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]) - 1;         if (s1[i - 1] == s2[j - 1]) {           dp[i][j] = max(dp[i][j], dp[i - 1][j - 1] + 2);           dp[i][j] = max(dp[i][j], 2);         }       }     }     ans = 0;     for (i = 0; i <= n; i++) {       for (j = 0; j <= m; j++) ans = max(ans, dp[i][j]);     }     cout << ans;   }   