/in/foo.c: In function 'main':
/in/foo.c:13:9: warning: 'Sn' may be used uninitialized [-Wmaybe-uninitialized]
   13 |         printf("%d\n",Sn);
      |         ^~~~~~~~~~~~~~~~~
/in/foo.c:5:15: note: 'Sn' was declared here
    5 |     int n,a,i,Sn,sum;
      |               ^~