#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
const int N = 1e3 + 5, OO = 0x3f3f3f3f, MOD = 1000000007, M = 200000 + 5;
const double EPS = 0.000000001;
int n, x, y;
char str[N];
int main() {
  scanf("%d %s", &n, str);
  for (int i = 0; i < n; ++i) {
    x += str[i] == 'R' ? 1 : str[i] == 'L' ? -1 : 0;
    y += str[i] == 'U' ? 1 : str[i] == 'D' ? -1 : 0;
  }
  x = abs(x);
  y = abs(y);
  printf("%d\n", n - x - y);
  return 0;
}
