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

ifstream fin("fact.in");
ofstream fout("fact.out");
 int main()
 {char a[1000],b[1000]={'Q','q','W','w','E','e','R','r','T','t','Y','y','U','u','I','i','O','o','P','p','A','a','S','s','D','d','F','f','G','g','H','h','J','j','K','k','L','l','Z','z','X','x','C','c','V','v','B','b','N','n','M','m','\0'};
  int nr=0,litere=0,k;
  while(!fin.eof())
    {fin>>a;
    nr++;
    k=strlen(a);
    for(unsigned int i=1;i<=strlen(a);i++)
        {bool c=0;
         for(unsigned int j=1;j<52;j++) {if(a[i]==b[j]) c=1; }
         if(c==0) k--;
        }
    litere=litere+k;
    }
    fout<<litere/nr;


   return 0;
 }