#include<iostream>
#include<fstream>
#include<string.h>
using namespace std;

int lungime,numar;

int ischar(char x){
	if(x>=65 and x<=90 ) return 1;
	if(x>=97 and x<=122) return 1;
	return 0;
}

void proces(){
	ifstream in("text.in");
	char c[60000];
	while(in>>c){
		lungime++;
		for(int i=0;i<strlen(c);i++)
			if(ischar(c[i]))numar++;
	}
	in.close();
}

int main(){
	proces();
	ofstream out("text.out");
	out<<numar/lungime;
	out.close();
	return 0;
}