/in/foo.c: In function 'main':
/in/foo.c:7:18: warning: statement with no effect [-Wunused-value]
    for(i=0;i++;i <= n)
                ~~^~~~
/in/foo.c:10:9: warning: implicit declaration of function 'pow' [-Wimplicit-function-declaration]
   k= k+ pow(10, i) *n;
         ^~~
/in/foo.c:10:9: warning: incompatible implicit declaration of built-in function 'pow'
/in/foo.c:10:9: note: include '<math.h>' or provide a declaration of 'pow'
/in/foo.c:13:2: warning: 'Sn' is used uninitialized in this function [-Wuninitialized]
  printf("%d", Sn);
  ^~~~~~~~~~~~~~~~