#include<cstring>
#include <fstream>
using namespace std;
ifstream fin("text.in");
ofstream fout("text.out");
char *p, a[5000],sep[]=" .,!";
int main ()
{
	fin.get(a,5000);
	int i=0,lit=0,cuv=0;
	while(a[++i])
	{
		if((a[i]>='a'&&a[i]<='z')||(a[i]>='A'&&a[i]<='Z'))
			lit++;
	}
	p=strtok(a,sep);
	do
	{
		cuv++;
		p=strtok(NULL,sep);
	}while (p);
	fout<<lit/cuv;
	return 0;
}