#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<math.h>
#include<complex>
#include<queue>
#include<deque>
#include<stack>
#include<map>
#include<set>
#include<bitset>
#include<functional>
#include<assert.h>
#include<numeric>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
using ll = long long;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;
const ll mod=1e9+7 ;


typedef vector<complex<double>> poly;
const double pi=acos(-1);

void dft(poly& f,int rev){
   int n=f.size();
   int j=0;
   REP(i,1,n-1){
      for(int k=n/2;k>(j^=k);k>>=1);
      if(i<j)swap(f[i],f[j]);
    }
   complex<double> zeta,ret,t,s;
   for(int i=1;i<n;i<<=1){
      zeta=polar(1.0,pi/i*rev);
      for(int j=0;j<n;j+=2*i){
         ret=1.0;
         rep(k,i){
              s=f[j+k];
              t=f[j+k+i];
              t=complex<double>(t.real()*ret.real()-t.imag()*ret.imag(),t.imag()*ret.real()+t.real()*ret.imag());
              f[j+k]=s+t;
              f[j+k+i]=s-t;
              ret*=zeta;
          }
       }
   }
    if(rev==-1)rep(i,n)f[i]/=n;
}

poly fft(poly& g,poly& h){
   poly f;
   int m=(int)g.size()+h.size()+1;
   int sz=1;
   while(sz<m)sz*=2;
   f.resize(sz,0);
   g.resize(sz,0);
   h.resize(sz,0);
   dft(g,1);
   dft(h,1);
   rep(i,sz)f[i]=g[i]*h[i];
   dft(f,-1);
   return f;
}


string s;

ll solve(int l,int r){
    if(r-l<2)return 0;
    int mid=(l+r)/2;
    poly f(r-l),g(r-l);
    REP(i,l,mid){
        if(s[i]=='U')f[i-l]=1;
    }
    REP(i,mid,r){
        if(s[i]=='G')g[i-l]=1;
    }
    poly ret = fft(f,g);
    ll ans=0;
    REP(i,l,r)if(s[i]=='M')ans+=(int)(ret[2*i-2*l].real()+.5);
    ans+=solve(l,mid);
    ans+=solve(mid,r);
    return ans;
}
int main(){
    int n;
    cin>>n;
    cin>>s;
    cout<<solve(0,n)<<endl;
    return 0;
}