#define _USE_MATH_DEFINES
#include<iostream>
#include<algorithm>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<deque>
#include<map>
#include<set>
#define ll long long
#define dou(s) atof(s.c_str())
#define lon(s) atoll(s.c_str())
#define str(n) to_string(n)
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define rrep(i,b,a) for(ll i=b;i>=a;i--)
#define ALL(a) a.begin(),a.end()
#define rALL(a) a.rbegin(),a.rend()
#define fion(n) fixed<<setprecision(n)
#define endl "\n"
#define OR ||
#define AND &&
#define NOT !
#define line(s) getline(cin,s)
#define MOD 1000000007ll
#define START int main(){cin.tie(0);ios::sync_with_stdio(false);
#define END }
using namespace std;
START
ll n,ans=0;string s;cin>>n>>s;
rep(i,0,n){
	if(s[i]=='U'){
		rep(j,i+1,n){
			if(s[j]=='M' AND 2*j-i<n AND s[2*j-i]=='G'){
				ans++;
			}
		}
	}
}
cout<<ans<<endl;
END