/in/foo.c: In function 'main':
/in/foo.c:7:11: warning: implicit declaration of function 'malloc' [-Wimplicit-function-declaration]
  a=(int *)malloc(10000*sizeof(int)); 
           ^~~~~~
/in/foo.c:7:11: warning: incompatible implicit declaration of built-in function 'malloc'
/in/foo.c:7:11: note: include '<stdlib.h>' or provide a declaration of 'malloc'
/in/foo.c:16:2: warning: implicit declaration of function 'free' [-Wimplicit-function-declaration]
  free(a);
  ^~~~
/in/foo.c:16:2: warning: incompatible implicit declaration of built-in function 'free'
/in/foo.c:16:2: note: include '<stdlib.h>' or provide a declaration of 'free'
/in/foo.c:6:14: warning: unused variable 'x' [-Wunused-variable]
  int n=0,i=0,x=0;
              ^