#include <bits/stdc++.h>
using namespace std;
#define FOR(i,n) for(int i=0;i<n;i++)
#define why(n,x) int n;while(cin >>n,n!=x)
#define iFOR(i,x,n)for(int i=x;i<n;i++)
#define unless(flg) if ( !(flg) )
#define read cin<<
#define echo cout<<
#define fin <<'\n'
#define __ <<" "<<
#define ___ <<" "
#define bash push_back
#define ALL(x) x.begin(),x.end()
#define SWAP(a,b) ((a != b) && (a += b,b = a - b,a -= b))
#define cinf(n,x) for(int UNCH=0;UNCH<(n);UNCH++) cin >> x[UNCH];
#define fcin(n,x) for(int UNCH=1;UNCH<=(n);UNCH++) cin>> x[UNCH];
#define memmin(x) memset((x),-1,sizeof((x)))
#define memzer(x) memset((x), 0,sizeof((x)))
#define meminf(x) memset((x),0x3f,sizeof((x)))
//#define int long long
typedef long long ll;
typedef pair < int , int >  pii;
typedef vector < int > vit;
typedef map < string , int > mstit;
typedef vector < pii > vpi ;
typedef greater < pii > gpi;
typedef priority_queue < pii , vpi , gpi > dijk ;
static const signed int INF = 0x3f3f3f3f;
static const signed long long LINF = 0x3f3f3f3f3f3f3f3fLL;
static const signed int SMOD = 1000000007;
static const signed int NMOD = 1000000009;
static const signed int dx[]={1,0,-1,0,1,1,-1,-1};
static const signed int dy[]={0,-1,0,1,-1,1,-1,1};

bool inside(int x,int y,int w,int h){return (x>=0 && y>=0 && x<w && y<h);}
template<class T>T abs(T &x){return x<0 ? -x : x;}
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
int qp(int a,ll b,int mo){int ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}
int gcd(int a,int b){return b?gcd(b,a%b):a;}


void solve(){

  int n,ans=0;
  string str;
  cin >> n >> str;
  FOR(i,n){
    iFOR(j,i+1,n){
      if(j+(j-i) >= n ) continue;
      if(str[i]=='U' && str[j] == 'M' && str[j+j-i]=='G')
        ans++;
    }
  }
  cout << ans fin;

  

}
struct xyz{ xyz(){ cin.tie(0), ios::sync_with_stdio(false); cout <<fixed<<setprecision(12);};}xyzzy;signed main(){solve();return 0;}