#include <bits/stdc++.h>
#include <algorithm>
#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define VRSORT(v) sort(v.rbegin(), v.rend());
#define ll long long
#define pb(a) push_back(a)
#define INF 999999999
#define MOD (ll)(1e9+7)
#define MAX (ll)(1e5*2+200)
#define print(x) cout << x << endl;
#define length(arr) sizeof arr / sizeof arr[0];
#define printArr(arr) REP(i, (sizeof arr / sizeof arr[0])){print(arr[i])}
#define printVec(vec) REP(i, vec.size()){print(vec[i])}
#define VMAX(v) max_element(v.rbegin(), v.rend())

using namespace std;


int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N;
    string S;
    cin >> N >> S;
    
    int k, ans = 0;
    FOR(i, 0, N){
        FOR(j, i+1, N){
            k = 2*j - i;
            if(N > k && k > j){
                if(S[i] == 'U' && S[j] == 'M' && S[k] == 'G'){
                    ans += 1;
                }
            }
        }
    }
    print(ans);
    
    return 0;
}