#include <bits/stdc++.h>
using namespace std;
int n, x, y, ans;
string s;
int main() {
  cin >> n;
  cin >> s;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'U') y++;
    if (s[i] == 'D') y--;
    if (s[i] == 'L') x--;
    if (s[i] == 'R') x++;
  }
  if (y < 0) y *= (-1);
  if (x < 0) x *= (-1);
  ans = n - x - y;
  cout << ans;
}
