#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <string>
#include <math.h>
#include <iomanip>
#include <limits>
#include <list>
#include <queue>
#include <tuple>
#include <map>
using namespace std;
#define MOD (long long int)(1e9+7)
#define ll long long int
#define rep(i,n) for(int i=0; i<(int)(n); i++)
#define reps(i,n) for(int i=1; i<=(int)(n); i++)
#define REP(i,n) for(int i=n-1; i>=0; i--)
#define REPS(i,n) for(int i=n; i>0; i--)
#define INF (int)(1123456789)
#define LINF (long long int)(112345678901234567)


int main(void){
	int n;
	string s;
	cin>>n;
	cin>>s;
	ll ans;
	rep(i,n-2){
		for(int j=i+1;j<n-1;j++){
			if(s[i] == 'U' && s[j] == 'M' && j+j-i < n && s[j+j-i] == 'G'){
				ans++;
			}
		}
	}
	cout<<ans<<endl;
	
	return 0;
}