#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;
ifstream fin("text.in");
ofstream fout("text.out");
int cuvinte,i, litere,x;
char s[100001];
int main()
{
    fin.getline(s,100001);
    x=strlen(s);
    for(i=0;i<x;i++)
        {if((s[i]>='a'&&s[i]<='z')||(s[i]>='A'&&s[i]<='Z')) litere++;
         if(strchr(" ,.:;!?-",s[i])&&((s[i-1]>='a'&&s[i-1]<='z')||(s[i-1]>='A'&&s[i-1]<='Z'))) cuvinte++;}
    fout<<litere/cuvinte;
    return 0;
}