#include<fstream>
using namespace std;

ifstream fin("text.in");
ofstream fout("text.out");

int nr, nrc, c;

int main()
{
	char a[10000];
	while(!fin.eof())
	{
	fin>>a;
	nr++;
	c=strlen(a);
	while(c)
	{
	if(isalpha(a[c-1]))
	nrc++;
	c--;
	}
	}
	fout<<(int)nrc/nr;
	return 0;
}