#include<iostream>
#include<fstream>
#include<string.h>
using namespace std;
ifstream f("text.in");
ofstream g("text.out");
char prop[100000];
int main()
{
int i,n,litere=0,cuv=0;
	while(f>>prop)
	{	
		cuv++;
		n=strlen(prop);
		for(i=0;i<n;i++)
		{
			if((int)prop[i]>=6&&(int)prop[i]<=90||(int)prop[i]>=97&&(int)prop[i]<=122)
			{
				litere++;
			}
			else
				if(i<n-1)
					cuv++;
		}
	}
	g<<litere/cuv;
}