C++ :

#include <stdio.h>

int c,big,little,L,i,j,k,n;

main(){
   scanf("%d",&c);
   while (c-- && (2 == scanf("%d%d",&L,&n))) {
      big = little = 0;
      for (i=0;i<n;i++) {
         scanf("%d",&k);
         if (k > big) big = k;
         if (L-k > big) big = L-k;
         if (k > L-k) k = L-k;
         if (k > little) little = k;
      }
      printf("%d %d\n",little,big);
   }
   if (c != -1) printf("missing input\n");
}