var x:char; c,l:real;   
f:text; ok:boolean;   
begin  
assign(f,'text.in');reset(f);read(f,x);   
c:=0;l:=0;ok:=false;   
while not eof(f) do begin  
      read(f,x);   
      if (x in ['A'..'Z']) or (x in ['a'..'z']) or (x in ['0'..'9']) then  
      if (x in ['A'..'Z']) or (x in ['a'..'z']) then begin l:=l+1; ok:=true; end  
      else if ok=true then begin l:=l+1; c:=c+1; ok:=false; end  
           else l:=l+1  
         else if ok=true then begin c:=c+1; ok:=false; end;   
       end;   
if (x in ['A'..'Z']) or (x in ['a'..'z']) or (x in ['0'..'9']) then c:=c+1;   
close(f);assign(f,'text.out');rewrite(f);   
if c<>0 then write(f,trunc(l/c)) else write(f,0);   
close(f);end.