#include <bits/stdc++.h>
#include <assert.h>

using namespace std;

int main()
{
  int n;
  string s;
  cin >> n >> s;
  int ans = 0;
  for (int i = 0; i < n; i++)
    if (s[i] == 'M')
      for (int j = 1; j <= min(n - i, i); j++)
        if (s[i - j] == 'U' && s[i + j] == 'G')
          ans++;
  cout << ans << endl;

  return 0;
}