#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int N;
    string S;
    cin >> N >> S;
    int ans = 0;
    rep(i,0,N)rep(j,i+1,N){
        int k = j * 2 - i;
        if(k >= N)break;
        if(S[i] == 'U' && S[j] == 'M' && S[k] == 'G'){
            ans++;
        }
    }
    cout << ans << endl;
}