/in/foo.c: In function 'main':
/in/foo.c:5:27: warning: unused variable 'sum' [-Wunused-variable]
  int r1=1,r2=1,medium,n,i,sum=0;
                           ^~~
/in/foo.c:15:3: warning: 'medium' may be used uninitialized in this function [-Wmaybe-uninitialized]
   printf("%d ",medium);
   ^~~~~~~~~~~~~~~~~~~~