#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;
ifstream fin("text.in");
ofstream fout("text.out");

int main()
{
    int n,i,cuvinte=0,litere=0;
    char x[1000000],*p;
    fin.getline(x,1000000);
    char sep[]=" ,?!;.-";
    n=strlen(x);
    for(i=1;i<=n;i++)
        if((x[i]>=65 && x[i]<=90) || (x[i]>=97 && x[i]<=122))
        litere++;
    p=strtok(x,sep);
    while(p)
    {
        cuvinte++;
        p=strtok(NULL,sep);
    }
    fout<<litere/cuvinte;
}