typedef long long ll;
#include <bits/stdc++.h>
using namespace std;
template<typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val){
    std::fill( (T*)array, (T*)(array+N), val );
}

int main() {
    ll n;
    string s;
    std::cin >> n;
    ll result = 0;
    std::cin >> s;
    for (int i =1; i <= n/2; i++) {
        for (int j = 0; j < n; j++) {
            ll c1,c2,c3;
            c1 = j;
            c2 = j+i;
            c3 = j+2*i;
            if(j+2*i>n-1)break;
            if( s[c1] == 'U' && s[c2] == 'M' && s[c3] == 'G'){
                result++;
            }
        }
    }
    std::cout << result << std::endl;
    
}