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

int isletter(char a)
{
	if( ('a'<=a && a<='z') || ('A'<=a && a<='Z'))
		return 1;
	return 0;
}
int main()
{
	long int letter=0,word=0;
	int i;
	FILE *in = fopen("text.in","r");
	freopen("text.out","w",stdout);
	char *text = (char*)malloc(1000000*sizeof(char));
	char *p;
	fgets(text,1000000,in);
	text[strlen(text)-1] = '\0';
	fclose(in);
	p = strtok(text,":,.- !?");
	while(p)
	{
		for(i=0;i<strlen(p);i++)
			if(isletter(p[i]))
				letter++;
		word++;
		p = strtok(NULL,":,.- !?");
	}
	printf("%ld\n",letter/word);

	return 0;
}