#include<iostream>
#include<fstream>
#include<string>
#include<algorithm>
#include<vector>
#include<cmath>
#include<stack>
#define MAXN 10000
using namespace std;
int main()
{
	freopen("cowa.in","r",stdin);
	freopen("cowa.out","w",stdout);
	long long i, j, k, a, b, n, ans=0;
	string word;
	cin>>n>>word;
	int cn=0, on=0, wn=0;
	for(i=0;i<n;i++)
	{
		if(word[i]=='C')
		{
			cn++;
		}
		if(word[i]=='O')
		{
			//cout<<cn<<' ';
			for(j=i;j<n;j++)
			{
				if(word[j]=='O')
				{
					on++;
				}
				if(word[j]=='W')
				{
					//cout<<on<<' ';
					for(k=j;k<n;k++)
					{
						if(word[k]=='W')
						{
							wn++;
						}
					}
					//cout<<wn<<endl;
					ans=ans+cn*on*wn;
					on=0;wn=0;
				}
			}
			cn=0;
		}
	}
	cout<<ans<<endl;
	return 0;
}