#include <fstream>
#include <cstring>
#define nmax 101
using namespace std;
ifstream fin("text.in");
ofstream fout("text.out");

void Solve()
{char s[10001],c[10001];
 long long sum=0,nr=0;
 int n=0,i;
 while(fin>>c)
 {i=0; n=0; strcpy(s,"");
  while(c[i]!=NULL)
  {if(c[i]>='a'&&c[i]<='z'||c[i]>='A'&&c[i]<='Z')
      {s[n++]=c[i]; s[n]=NULL;}
   else
   {if(n>0) nr++;
    sum+=n; n=0;
    strcpy(s,"");
   }
   i++;
  }
 if(n>0) {sum+=n; nr++;}
 }
 if(nr>0) fout<<sum/nr<<endl;
 else fout<<0<<endl;
}

int main()
{Solve();
 return 0;
}