#include<fstream>
using namespace std;
ifstream f("text.in");
ofstream g("text.out");
int main(){
    unsigned l=0, c=0;
    char c;
    do{
         c=getchar();
         if (c=="a" || c=="b" || c=="c" || c=="d" || c=="e" || c=="f" || c=="g" || c=="h" || c=="i" || c=="j" || c=="k" || c=="l" || c=="m" || c=="n" || c=="o" || c=="p" || c=="q" || c=="r" || c=="s" || c=="t" || c=="u" || c=="v" || c=="w" || c=="x" || c=="y" || c=="z") l++;
         if (c==" " || c==";" || c==":" || c=="&") c++;}    
    while(c!="." || c!="?" || c!="!")
g<<l/c;
f.close();
g.close();
return 0;
}