#include<stdio.h>
#include<string.h>
int main()
{long n,i,s=0,j,k=0,r,ok;
char v[100],l;
FILE *f=fopen("text.in","r");
FILE *g=fopen("text.out","w");
while (!feof(f))
	{fscanf(f,"%s",&v);
	j=strlen(v);
	s=s+j; k++;
	r=0;      ok=0;
	for (i=2;i<=j-1;i++)
		{ok=0;
		for (l='a';l<='z';l++)
			if ((int)v[i]==(int)l) {ok=1;break;}
		if (ok==0) {s--;k++;}}}
fprintf(g,"%ld",s/k);
fclose(f);
fclose(g);
return 0;}