# include <fstream>
# include <cstring>
# include <iostream>
using namespace std;
ifstream f("text.in");
ofstream g("text.out");
long long k,sum;
char c1,c2,s[]="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
int main()
{
    c1=' ';sum=k=0;
    while(f.get(c2))
    {
        if(strchr(s,c2)!=NULL)sum++;
        else {if(strchr(s,c1)!=NULL)k++;}
        c1=c2;
    }
    g<<sum/k;
}