#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
#include <map>
#include <stdio.h>
#include <math.h>
#include <iomanip>
#include <queue>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double lld;

#define rep(i,n) for(int i = 0; i < (n); i++)
#define pb push_back 
#define eb emplace_back 
#define fi first
#define se second
#define all(x) x.begin() , x.end()
#define vi vector<int>
#define vll vector<ll>
#define vb vector<bool>
#define vs vector<string>
#define mp make_pair

const static int INF = 1001001001;
const static ll LINF = 1001001001001001001LL;
const static lld PI = 3.1415926535897932384626L;
const static int MOD = 1000000009;
//const static int MOD = 998244353;

template < typename T > bool chmin (T &a , T b) { if (a > b) { a = b; return true; } else { return false; } }
template < typename T > bool chmax (T &a , T b) { if (a < b) { a = b; return true; } else { return false; } }
ll gcd (ll a , ll b) { if (a < b) swap(a , b); if (a % b == 0) return b; else return gcd (b , a % b); }
ll lcm (ll a , ll b) { return (a / gcd (a , b) * b); }
int keta (ll x) { int ret = 0; while(x) { ret++; x /= 10; } return ret; }
inline int in () { int x; scanf("%d" , &x); return x; }
inline ll lin () { ll x; scanf("%lld" , &x); return x; }
inline string sin () { string s; cin >> s; return s; }

void io_setup () {
    cout << fixed << setprecision(15);
    //cin.tie(0);
    //ios::sync_with_stdio(false);
}

bool is_prime (ll x) {
    if (x == 2 || x == 3 || x == 5 || x == 7) {
        return true;
    }
    for (ll i = 3; i * i <= x; i++) {
        if (x % i == 0) {
            return false;
        }
    }
    return true;
}

/*
vb prime_table(2020202 , true);
void prime () {
    prime_table[0] = false;
    prime_table[1] = false;
    for (int i = 2; i < 2020202; i++) {
        for(int j = i + i; j < 2020202; j += i) {
            prime_table[j] = false;
        }
    }
}
*/

//nCr
ll modpow (ll x , ll p) {
    ll ret = 1;
    while (p > 0) {
        if (p & 1) {
            ret *= x;
            ret %= MOD;
        }
        x *= x;
        x %= MOD;
        p >>= 1;
    }
    return ret;
}

vector<ll> fact(1 << 20 , 0);
vector<ll> factinv(1 << 20 , 0);

void pre_calc_fact () {
    fact[0] = 1;
    for (int i = 1; i < (1 << 20); i++) {
        fact[i] = 1LL * i * fact[i - 1] % MOD;
    }
    for (int i = 0; i < (1 << 20); i++) {
        factinv[i] = modpow(fact[i], MOD - 2);
    }
}

ll nCk (ll n , ll k) {
    return fact[n] * factinv[k] % MOD * factinv[n - k] % MOD;
}

/*
//memo
v.erase(unique(all(v)), v.end());
*/

void solve() {
    int n = in();
    string s;
    cin >> s;
    int ans = 0;
    for (int i = 0; i < n - 2; i++) {
        for (int j = i + 1; j < n - 1; j++) {
            if (s[i] == 'U' && s[j] == 'M') {
                int k = j + j - i;
                if (k < n && s[k] == 'G') ans++;
            }
        }
    }
    cout << ans << endl;
    return;
}

int main () {
    io_setup();
    //prime();
    //pre_calc_fact();
    solve();
    return 0;
}