#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

char buf[1000000000+1];

int main(void)
{
	char *s;
	double nr_cuv=0;
	double lungime_cuv=0;
	freopen("text.in","r",stdin);
	freopen("text.out","w",stdout);
	while(fgets(buf,1000000000,stdin))
	{
		s=strtok(buf," ,.-;:!?01234\"\'56789");
		while(s!=NULL)
		{
			++nr_cuv;
			lungime_cuv+=strlen(s);
			s=strtok(NULL," ,.-;:!?01234\"\'56789");
		}
	}
	printf("%lf",floor(lungime_cuv/nr_cuv));
	return 0;
}