/in/foo.cc: In function 'int main()':
/in/foo.cc:17:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&N);
                   ^
/in/foo.cc:20:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%s",a);
                      ^