/in/foo.c: In function 'main':
/in/foo.c:8:2: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
  scanf("%d",&n);
  ^~~~~
/in/foo.c:8:2: warning: incompatible implicit declaration of built-in function 'scanf'
/in/foo.c:8:2: note: include '<stdio.h>' or provide a declaration of 'scanf'
/in/foo.c:13:9: warning: implicit declaration of function 'fabs' [-Wimplicit-function-declaration]
    b[j]=fabs(a[j]-a[k])+b[j];
         ^~~~
/in/foo.c:13:9: warning: incompatible implicit declaration of built-in function 'fabs'
/in/foo.c:13:9: note: include '<math.h>' or provide a declaration of 'fabs'
/in/foo.c:15:2: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
  printf("%d",count);
  ^~~~~~
/in/foo.c:15:2: warning: incompatible implicit declaration of built-in function 'printf'
/in/foo.c:15:2: note: include '<stdio.h>' or provide a declaration of 'printf'