#include <iostream>
#include <fstream>
using namespace std;
ifstream f("text.in");
ofstream g("text.out");
char c;
inline bool lit(char c)
{
    return ('a'<=c&&c<='z')||('Z'<=c&&c<='Z');
}
int main()
{
    int n=0, l=0;
    f>>noskipws;
    while(f>>c)
    {
        if(lit(c))while(f>>c)l++;
        n++;
    }
    g<<l/n;
    return 0;
}