#include <algorithm>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <queue>
#include <stack>
#include <utility>
#include <vector>
using std::cerr;
using std::cin;
using std::cout;
using std::endl;

void OutputError(std::string s) {
  cerr << "\033[93m" << s << "\033[m" << endl;
  return;
}

int main(void) {
  cout << std::fixed << std::setprecision(10);
  cin.tie(0);
  std::ios::sync_with_stdio(false);
  int n;
  std::string s;
  cin >> n >> s;
  int result = 0;
  for (int center = 1; center < n - 1; center++) {
    if (s[center] == 'M') {
      int width = 1;
      while (center - width >= 0 && center + width < n) {
        int left = center - width, right = center + width;
        if (s[left] == 'U' && s[right] == 'G') {
          result++;
        }
        width++;
      }
    }
  }
  cout << result << endl;
  return 0;
}