#include <iostream>
#include <string>
using namespace std;
int main(int argc, char* argv[])
{
	int N;
	cin>>N;
	string S;
	cin>>S;
	int i,j,k,num=0;
	int Unum=0,Mnum=0,Gnum=0;
	for (i=0;i<N;i++){
		switch(S[i]){
			case 'U':
				Unum=1;
				break;
			case 'M':
				Mnum=1;
				break;
			case 'G':
				Gnum=1;
				break;
		}
		if (Unum+Mnum+Gnum==3){
			break;
		}
	}
	if (Unum+Mnum+Gnum<3){
		cout<<0<<endl;
		return 0;
	}
	for (i=1;i<=N-2;i++){
		for (k=i+2;k<=N;k++){
			if ((i+k)%2==0){
				j=(i+k)/2;
				if (S[i-1]=='U' &&S[j-1]=='M' &&S[k-1]=='G'){
					num++;
				}
			}
		}
	}
	cout<<num<<endl;
	return 0;
}