rt，WA on #1 and #6

#include <bits/stdc++.h>
using namespace std;
string x, y;
long long dp[3][11451];
int main() {
  cin >> x >> y;
  int len1 = x.size(), len2 = y.size();
  x += ' ';
  y += ' ';
  for (int i = 1; i <= len1; i++) {
    for (int j = 1; j <= len2; j++) {
      if (x[i] == y[j]) dp[i % 2][j] = dp[(i - 1) % 2][j - 1] + 1;
        else dp[i % 2][j] = max(dp[(i - 1) % 2][j], dp[i % 2][j - 1]);
    }
  } cout << dp[len1 % 2][len2];
  return 0;
}