#include<bits/stdc++.h>
using namespace std;
namespace my_std{
	#define ll long long
	#define bl bool
	ll my_pow(ll a,ll b,ll mod){
		ll res=1;
		if(!b) return 1;
		while(b){
			if(b&1) res=(res*a)%mod;
			a=(a*a)%mod;
			b>>=1;
		}
		return res;
	}
	ll qpow(ll a,ll b){
		ll res=1;
		if(!b) return 1;
		while(b){
			if(b&1) res*=a;
			a*=a;
			b>>=1;
		}
		return res;
	}
	#define db double
	#define pf printf
	#define pc putchar
	#define fr(i,x,y) for(register ll i=(x);i<=(y);i++)
	#define pfr(i,x,y) for(register ll i=(x);i>=(y);i--)
	#define go(u) for(ll i=head[u];i;i=e[i].nxt)
	#define enter pc('\n')
	#define space pc(' ')
	#define fir first
	#define sec second
	#define MP make_pair
	#define il inline
	#define inf 8e18
	#define random(x) rand()*rand()%(x)
	#define inv(a,mod) my_pow((a),(mod-2),(mod))
	il ll read(){
		ll sum=0,f=1;
		char ch=0;
		while(!isdigit(ch)){
			if(ch=='-') f=-1;
			ch=getchar();
		}
		while(isdigit(ch)){
			sum=sum*10+(ch^48);
			ch=getchar();
		}
		return sum*f;
	}
	il void write(ll x){
		if(x<0){
			x=-x;
			pc('-');
		}
		if(x>9) write(x/10);
		pc(x%10+'0');
	}
	il void writeln(ll x){
		write(x);
		enter;
	}
	il void writesp(ll x){
		write(x);
		space;
	}
}
using namespace my_std;
ll n,a[7575],cnt=0,tree1[20020],tree2[20020],sum[7575],res1=0,res2=0,ans=0;
char s[7575];
il ll lowbit(ll x){
	return x&(-x);
}
il void mdf(ll x,ll v){
	ll tmp=v*x;
	while(x<=2*n){
		tree1[x]+=v;
		tree2[x]+=tmp;
		x+=lowbit(x);
	}
}
il void query(ll l,ll r){
	if(l>r) return;
	while(r){
		res1+=tree1[r];
		res2+=tree2[r];
		r-=lowbit(r);
	}
	l--;
	while(l){
		res1-=tree1[l];
		res2-=tree2[l];
		l-=lowbit(l);
	}
}
int main(){
	scanf("%s",s+1);
	n=strlen(s+1);
	fr(i,1,n) if(s[i]=='G') a[++cnt]=i;
	a[cnt+1]=n+1;
	fr(mid,1,cnt){
		ll l=mid-min(cnt-mid,mid-1),r=mid+min(cnt-mid,mid-1);
		fr(i,1,2*n) tree1[i]=tree2[i]=0;
		while(l<r){
			fr(i,a[l-1]+1,a[l]) fr(j,a[r],a[r+1]-1) mdf(i+j,1);
			res1=res2=0;
			query(1,a[l]+a[r]);
			ans+=(a[l]+a[r])*res1-res2;
			res1=res2=0;
			query(a[l]+a[r]+1,2*n);
			ans+=res2-(a[l]+a[r])*res1;
			l++;
			r--;
		}
		fr(i,a[l-1]+1,a[l]) fr(j,a[r],a[r+1]-1) mdf(i+j,1);
		res1=res2=0;
		query(1,2*a[l]);
		ans+=a[l]*res1-res2/2;
		res1=res2=0;
		query(2*a[l]+1,2*n);
		ans+=res2/2-a[l]*res1;
	}
	fr(mid,1,cnt){
		ll l=mid-min(cnt-mid,mid-1),r=mid+min(cnt-mid,mid-1);
		fr(i,1,2*n) tree1[i]=tree2[i]=0;
		while(l<r){
			fr(i,a[l-1]+1,a[l]) fr(j,a[r],a[r+1]-1) if((i+j)%2==1) mdf(i+j,1);
			res1=res2=0;
			query(1,a[l]+a[r]);
			ans-=(a[l]+a[r])*res1-res2;
			res1=res2=0;
			query(a[l]+a[r]+1,2*n);
			ans-=res2-(a[l]+a[r])*res1;
			l++;
			r--;
		}
		fr(i,a[l-1]+1,a[l]) fr(j,a[r],a[r+1]-1) if((i+j)%2==1) mdf(i+j,1);
		res1=res2=0;
		query(1,2*a[l]);
		ans-=a[l]*res1-res2/2;
		res1=res2=0;
		query(2*a[l]+1,2*n);
		ans-=res2/2-a[l]*res1;
	}
	fr(mid,1,cnt-1){
		ll l=mid-min(cnt-mid-1,mid-1),r=mid+1+min(cnt-mid-1,mid-1);
		fr(i,1,2*n) tree1[i]=tree2[i]=0;
		while(l<r){
			fr(i,a[l-1]+1,a[l]) fr(j,a[r],a[r+1]-1) mdf(i+j,1);
			res1=res2=0;
			query(1,a[l]+a[r]);
			ans+=(a[l]+a[r])*res1-res2;
			res1=res2=0;
			query(a[l]+a[r]+1,2*n);
			ans+=res2-(a[l]+a[r])*res1;
			l++;
			r--;
		}
	}
	fr(i,1,n) sum[i]=sum[i-1]+(s[i]=='G');
	fr(i,1,n) fr(j,i,n) if((j-i+1)%2==0&&(sum[j]-sum[i-1])%2==1) ans--;
	write(ans);
}