#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

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