foo.c: In function 's':
foo.c:18:8: warning: unused variable 'flag' [-Wunused-variable]
   18 |  int i,flag=1;
      |        ^~~~
foo.c:29:1: warning: control reaches end of non-void function [-Wreturn-type]
   29 | }
      | ^
foo.c: In function 'main':
foo.c:33:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   33 |  scanf("%d",&a);
      |  ^~~~~~~~~~~~~~

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