#include <bits/stdc++.h>
  
using namespace std;
  
#define rep(i,n) REP(i,0,n)
#define REP(i,s,e) for(int i=(s); i<(int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for(int i=(int)(s-1); i>=(int)(e); i--)
#define pb push_back
#define all(r) r.begin(),r.end()
#define rall(r) r.rbegin(),r.rend()
#define fi first
#define se second
  
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
 
const int INF = 1e9;
const ll MOD = 1e9 + 7;
double EPS = 1e-8;

int main(){
    int n;
    string s;
    cin >> n >> s;
    int ans = 0;
    REP(j, 1, n-1) if(s[j] == 'M') {
        REP(d, 1, n+1) {
            int i = j - d, k = j + d;
            if(i < 0 || k >= n) break;
            if(s[i] == 'U' && s[k] == 'G') ++ans;
        }
    }
    cout << ans << endl;
    return 0;
}