#include <bits/stdc++.h>
typedef long long ll;
#define FOR(i,a,b) for(ll i=(a);i<(b);i++)
#define REP(i,a) FOR(i,0,a)
using namespace std;
const ll MAX_N=5000;
ll N;
char S[MAX_N+1];
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin>>N>>S;
	ll ans=0;
	REP(i,N){
		FOR(j,i+1,N){
			ll k=2*j-i;
			if(k<N && S[i]=='U' && S[j]=='M' && S[k]=='G'){
				ans++;
			}
		}
	}
	cout<<ans<<endl;
}