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

FILE *in,*out;
char s[25000];
int nrcuv,i,lit;
long long sum;
int main()
{
	in=fopen("text.in","rt");
	out=fopen("text.out","wt");
	while(!feof(in))
	{
		memset(s,NULL,strlen(s));
		fscanf(in,"%s",s);
		lit=0;
		for(i=0;i<=strlen(s);i++)
		{
			if( (s[i]>=65 && s[i]<=90) || (s[i]>=97 && s[i]<=122) )
			{
				lit++;
			}
			else
			{
				if(lit)
				{
					sum+=lit;
					lit=0;
					nrcuv++;
				}
			}
		}
	}
	fprintf(out,"%lld",(sum/nrcuv));
	return 0;
}