#include <string>
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    int nrlit=0,nrcuv=0;
    char c,c1;
    bool k;
    FILE *f=fopen("text.in","r");
    while(fscanf(f,"%c",&c)==1)
    {
        if((c>='a'&&c<='z')||(c>='A'&&c<='Z')){
        nrlit++;k=0;}
        else while(fscanf(f,"%c",&c1)==1)if((c1>='a'&&c1<='z')||(c1>='A'||c1<='Z') ){k=1;break;}
        if(k==1&&nrlit)
        nrcuv++;
        if(k==1&&((c1>='a'&&c1<='z')||(c1>='A'||c1<='Z'))&&(c1!=' '&&c1!=0))nrlit++;
    }
    ofstream("text.out")<<(nrlit)/nrcuv;
    return 0;
}