#include<stdio.h>#include<string.h>#include<stdlib.h>#include<math.h>#include<algorithm>using namespace std;struct point{ double x; double y;}p[20];struct T{ int xx;// int yy;// int zz;// double mianji;//}res;bool cmp(int a,int b){ return a<b;}point operator-(const point &a,const point &b){ point temp; temp.x=a.x-b.x; temp.y=a.y-b.y; return temp;}double operator*(const point &a,const point &b){ return fabs(a.x*b.y-b.x*a.y);}double cal(point a,point b,point c){ point m=b-a; point n=c-a; return m*n/2;}double cal2(point a,point b,point c,point d){ point m=c-d; point n=a-d; point h=b-d; return m*n/2+m*h/2+n*h/2;}int main(){ int n; while(scanf("%d",&n),n) { res.xx=-1; res.yy=-1; res.zz=-1; res.mianji=0; getchar(); int i,j,k,l; char ch; for(i=0;i<n;i++) { scanf("%c",&ch); scanf("%lf %lf",&p[i].x,&p[i].y); getchar(); } double mianji1,mianji2; for(i=0;i<n;i++) { for(j=i+1;j<n;j++) { for(k=j+1;k<n;k++) { //由p[i],p[j],p[k]组成的三角形 mianji1=cal(p[i],p[j],p[k]); bool flag=true; for(l=0;l<n;l++) { if(l==i||l==j||l==k) { continue; } mianji2=cal2(p[i],p[j],p[k],p[l]); if(mianji1==mianji2) { flag=false; break; } } if(flag)//三角形合法 { if(mianji1>res.mianji) { res.xx=i; res.yy=j; res.zz=k; res.mianji=mianji1; } } } } } int h[3]; h[0]=res.xx; h[1]=res.yy; h[2]=res.zz; sort(h,h+3,cmp); printf("%c%c%cn",h[0]+'A',h[1]+'A',h[2]+'A'); } return 0;}
