#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<int(n); ++i)
#define repll(i,m,n) for(ll i=m; i<ll(n); ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define fi first
#define se second

template<typename T> bool chmin(T& a, T b){ if(a > b){a = b; return true;} return false; }
template<typename T> bool chmax(T& a, T b){ if(a < b){a = b; return true;} return false; }

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N;
    string S;
    cin >> N >> S;

    ll ans = 0LL;
    for(int i = 0; i < N; ++i){
        if(S[i] != 'U') continue;
        for(int j = i+1; j < N; ++j){
            if(S[j] != 'M') continue;
            int k = 2*j - i;
            if(k >= N) continue;
            if(S[k] == 'G') ++ans;
        }
    }
    cout << ans << endl;

    return 0;
}