#include <fstream>
#include<cstring>
using namespace std;
ifstream f("text.in");
ofstream g("text.out");
int main()
{int nrcuv=0,nrl=0;
   string s;
   while(f>>s)
   {int ok=0,per=0;
       for(int i=0;i<s.size();i++)
    if(!isalpha(s[i]))ok++; else per++;
    if(!isalpha(s[s.size()-1]))ok--;
       nrl=nrl+per;
       if(per!=0)nrcuv=nrcuv+ok+1;
   }
   g<<nrl/nrcuv;
    return 0;
}