#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <limits.h>
#include <map>
#include <queue>
#include <set>
#include <string.h>
#include <vector>

using namespace std;
typedef long long ll;

int main() {
  int N;
  string S;

  cin >> N;
  cin >> S;

  int ans = 0;

  for (int i = 0; i < N; ++i) {
    for (int j = i + 1; j < N; ++j) {
      int k = 2 * j - i;

      if (S[i] == 'U' && S[j] == 'M' && S[k] == 'G') {
        ++ans;
      }
    }
  }

  cout << ans << endl;

  return 0;
}