typedef struct{double x,y,k;}w;w p[101],b;m,v[100],n,j;z(w*c,w*d){return c->k>d->k?-1:c->k<d->k;}double o(q,r,s){return p[q].x*(p[r].y-p[s].y)+p[r].x*(p[s].y-p[q].y)+p[s].x*(p[q].y-p[r].y);}main(i){double k,t;for(;~scanf("%d",&n),j=n;){for(m=i=0;i<n;i++)scanf("%lf,%lf",&p[i].x,&p[i].y),p[m].y>p[i].y?m=i:0;b=p[m];p[m]=*p;*p=b;p[100].x=b.x;p[100].y=b.y+1;for(i=1;i<n;i++){k=o(0,i,100);t=(p[i].x-b.x)*(p[i].x-b.x)+(p[i].y-b.y)*(p[i].y-b.y);k*=k/t;if(b.x>p[i].x)k=-k;p[i].k=k;}qsort(p+1,n-1,sizeof(w),z);v[0]=0;v[1]=1;v[2]=j=2;for(i=3;i<n;i++){for(;o(v[j-1],v[j],i)<=0;j--);v[++j]=i;}printf("%d\n",n+~j);}}