#include <cstdio>
#include <string.h>
#include <ctype.h>
int main()
{
	int medie=0,nr=0;
	FILE*fin;
	FILE*fout;
	fin=fopen("text.in","r");
	fout=fopen("text.out","w");
	while(!feof(fin))
	{
		char c[1000000];
		fscanf(fin,"%s",c);
		medie+=strlen(c);
		for(int i=0;i<strlen(c);i++)
			if(!isalpha(c[i]))
				medie--;
		nr++;
	}
	medie/=nr;
	fprintf(fout,"%d",medie);
}