# include <fstream>
# include <string.h>

using namespace std;

int main ()
{
    char t[1001];
    unsigned lit=0,cuv=0,aux;
    ifstream fin ("text.in");
    ofstream fout("text.out");

    while(fin.get(t,1001))
    {
        for(int i = 0; i < strlen(t); i++)
       {if((t[0] >= 'a' && t[0]<='z')||(t[0]>='A'&&t[0]<='Z'))
           {if((t[i] >= 'a' && t[i]<='z')||(t[i]>='A'&&t[i]<='Z'))
        lit++;
            if((t[i+1]>=' '&& t[i+1]<='@')&& (t[i] >= 'a' && t[i]<='z')||(t[i]>='A'&&t[i]<='Z'))
        cuv++;
        aux=1;
        }
         if(t[0]>=' '&& t[0]<='@')
           {if((t[i] >= 'a' && t[i]<='z')||(t[i]>='A'&&t[i]<='Z'))
        lit++;
            if((t[i]>=' '&& t[i]<='@')&& (t[i+1] >= 'a' && t[i+1]<='z')||(t[i+1]>='A'&&t[i+1]<='Z'))
        cuv++;
        }

    }}
    if(aux==1)
    cuv=cuv-1;
    if(cuv==0)
    fout<<0;
 else
   fout<<lit/cuv;
   fin.close();
   fout.close();
    return 0;
}