#include <iostream>
#include <string>

using namespace std;

int main() {
  int n;
  string s;
  int c = 0;
  cin >> n >> s;
  for (int i = 0; i < n-2; ++i) {
    for (int j = i+1; j < n-1; ++j) {
      int k = 2*j - i;
      if (s[i] == 'U' && s[j] == 'M' && s[k] == 'G') c++;
    }
  }

  cout << c << endl;
}