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

ifstream in("text.in");
ofstream out("text.out");

int main()
{
    char a[1024];
    int nrlit = 0, nrcuv = 0;
    in.getline(a, 1024);
    int n = strlen(a);
    for(int i = 0; i<n;i++)
        if(('a'<=a[i] && a[i] <= 'z') ||('A'<=a[i] && a[i] <= 'Z'))
            nrlit++;
    char * p;
    p = strtok (a," ,.:?!-0123456789");
    while (p != NULL)
    {
    nrcuv++;
    p = strtok (NULL, " ,.:?!-0123456789");
    }
    out<<nrlit/nrcuv;
    return 0;
}