#include <stdio.h>
#include <string.h>
#include <math.h>
#define lon(x) ll[x][0]
#define lat(x) ll[x][1]
#define writetofile 1
#define d(x,y) ((x==y)?0:(x<y)?dist[x][y]:dist[y][x])
#define cs(x) cos(x*0.00000001745329251994)
#define sn(x) sin(x*0.00000001745329251994)

int ll[1001][2],c1,c2,n,notdunn;
int ff, minD=50000, dist[1001][1001];
char *w,label,lab[1001][4],j;
FILE *myfile, *labfile;

main ()
{ if ((myfile = fopen("city.ll", "r")) == NULL)
  { fprintf(stderr,"error opening data file.\n");
    exit(1);
  }
  notdunn=1;
  n=0;
  while (notdunn)
  { fscanf(myfile,"%d %d",ll[n],ll[n]+1);
    if (notdunn = lon(n)+lat(n))
    { n++;
    }
  }
  printf("%d cities\n",n);

  fclose (myfile);
  label=1-writetofile;
  if (label)
  { if ((labfile = fopen("city.nm", "r")) == NULL)
    { fprintf(stderr,"no label file.\n");
      label=0;
    }
    if (label)
    { for (c1=0;c1<n;c1++)
      { fscanf(labfile,"%s",lab[c1]);
      }
      fclose (labfile);
    }
  }
  if (writetofile)
  { if ((myfile = fopen("city.mtx", "w")) == NULL)
    { fprintf(stderr,"error opening output file.\n");
      exit(1);
    }
  }
  else {myfile = stdout;}
  
  for (c1=0;c1<n-1;c1++)
  { for (c2=c1+1;c2<n;c2++)
    { ff = dist[c1][c2] = acos(
           cs(lon(c1))*cs(lat(c1))*cs(lon(c2))*cs(lat(c2))+
           sn(lon(c1))*cs(lat(c1))*sn(lon(c2))*cs(lat(c2))+
           sn(lat(c1))*sn(lat(c2))         )*63781.5;
      minD = (ff<minD)?ff:minD;
  } }
  printf("Minimum Distance: %d\n",minD);
  if (label) {printf(" ");for(c1=0;c1<n;c1++){printf("     %s",lab[c1]);}printf("\n");}
  for (c1=0;c1<n;c1++)
  { if (label) {printf("%s ",lab[c1]);}
    for (c2=0;c2<n;c2++)
    { fprintf(myfile,"%5d ",d(c1,c2));
    }
    fprintf(myfile,"\n");
  }
}