#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
using ll=long long;
char s[7505];
int pl[7505],cnt[15005];
int main(){
	cin>>(s+1);
	int n=strlen(s+1),m=0;
	for(int i=1;i<=n;++i)if(s[i]=='G')pl[++m]=i;
	ll ans=0;
	for(int i=1;i<=m;++i)
		for(int j=i;j<=i+1&&j<=m;++j){
			ll sum=0,d=0;memset(cnt,0,sizeof cnt);
			for(int k=0;i-k>=1&&j+k<=m;++k){
				int u=pl[i-k],um=i-k==0?1:pl[i-k-1]+1;
				int v=pl[j+k],vm=j+k==m?n:pl[j+k+1]-1;
				if(u<v)cnt[u+v]+=2,++d;
				for(int l=u;l>=um;--l){
					for(int r=v;r<=vm;++r){
						if(i==j)ans+=r-l&1?-1:sum+abs((l+r>>1)-pl[i]);
						else ans+=sum;
						sum+=d;d+=cnt[l+r+1];
					}
					for(int r=vm+1;r>=v;--r)d-=cnt[l+r],sum-=d;
				}
				for(int r=v;r<=vm;++r)sum+=d,d+=cnt[um+r];
			}
		}
	cout<<ans<<'\n';
	return 0;
}