#include<cstdio>
#include<cstring>
int l,i,j,nr,nc,a;
char s[2000100],*p,c;
FILE *f,*g;
int main(){
    f=fopen("text.in","r");
    g=fopen("text.out","w");
    while(!feof(f)){
        //fgets(s,3000000,f);
        fscanf(f,"%s",s);
        l=strlen(s);
        a=0;
        for(i=0;i<l;i++){
            if((s[i]>='a'&&s[i]<='z')||(s[i]>='A'&&s[i]<='Z'))
                a++;
            else{
                if(a!=0){
                    nc+=a;
                    a=0;
                    nr++;
                }
            }
        }
        if(a!=0){
        nr++;
        nc+=a;
    }
    }
    if(a!=0){
        nr++;
        nc+=a;
    }
    if(nr!=0)
        fprintf(g,"%d",nc/nr);
    else
        fprintf(g,"0");








    fclose(f);
    fclose(g);
    return 0;
}