/in/foo.c: In function 'main':
/in/foo.c:7:23: warning: statement with no effect [-Wunused-value]
    for (i = 0; i++; i <= n)
                     ~~^~~~
/in/foo.c:10:14: warning: implicit declaration of function 'pow' [-Wimplicit-function-declaration]
      k = k + pow(10, i) * n;
              ^~~
/in/foo.c:10:14: warning: incompatible implicit declaration of built-in function 'pow'
/in/foo.c:10:14: note: include '<math.h>' or provide a declaration of 'pow'
/in/foo.c:14:5: warning: 'Sn' is used uninitialized in this function [-Wuninitialized]
     printf("%d", Sn);
     ^~~~~~~~~~~~~~~~