#include<fstream>
#include<cstring>
#include<iostream>
using namespace std;
int main()
{char c[333];
 int cuv=0,lit=0,i;
 ifstream f("text.in");
 while (!f.eof())
 {f>>c;
  if(strlen(c)==1)
    if((c[0]>='a' && c[0]<='z') || (c[0]<='Z' && c[0]>='A'))
	 {lit++;
	  cuv++;
	  f>>c;
	 }
	 else
	  {f>>c;
	   cuv++;
	  }
  for (i=0;i<strlen(c);i++)
   if((c[i]>='a' && c[i]<='z') || (c[i]<='Z' && c[i]>='A'))
	  lit++;
	  cuv++;
 }
ofstream g("text.out");
 g<<lit/cuv;
 f.close();
 g.close();
 return 0;
}