#include <bits/stdc++.h>

#define foreach(i, v) for(__typeof((v).begin()) i = (v).begin(); i != (v).end(); ++ i)
#define BETWEEN(a, x, b) (a<=x&&x<b)

using namespace std;
typedef long long ll;

int main(int argc, char *argv[]) {
  ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);

  int n;string s;cin>>n>>s;
  int res = 0;
  for(int step=1;step<n;step++){
    for(int pos = 0;pos < n; pos++) {
      if(pos + step * 2 >= n) break;
      if (s[pos] == 'U' && s[pos + step] == 'M' && s[pos + step*2] == 'G')
        res++;
    }
  }
  cout<<res<<endl;

  return 0;
}