#include <iostream>
#include <string.h>

using namespace std;
char s[1001],*p;
ifstream f("text.in");
ofstream g("text.out");
int nrcuv,lit;
int main()
{
    f.getline(s,100);
    p=strtok(s," ;,:");
    while(p)
    {
        nrcuv++;
        for(int i=0;i<strlen(p);i++)
            if((p[i]>='a' && p[i]<='z') || (p[i]>='A' &&p[i]<='Z'))
              lit++;
        p=strtok(NULL," -;,:?!");
    }

    g<<lit/nrcuv;
    f.close();g.close();
    return 0;
}