#include <fstream>
#include <string.h>
using namespace std;
ifstream fi("text.in");
ofstream fo("text.out");
char L[2000000];
char *p;
int i;
int nrlit;
int nrcuv;
int main()
{
	fi.getline(L,2000000);
	nrlit=0;
	for (i=0;L[i]!='\0';i++)
		if (!((L[i]>='a' && L[i]<='z') || (L[i]>='A' && L[i]<='Z')))
			L[i]=' ';
		else
			nrlit++;
	nrcuv=0;
	p=strtok(L," ");
	while (p!=NULL)
	{
		nrcuv++;
		p=strtok(NULL," ");
	}
	fo<<nrlit/nrcuv;
	fi.close();
	fo.close();
	return 0;
}