foo.cc: In function 'int main()':
foo.cc:11:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%d%d",&n,&k);
 ~~~~~^~~~~~~~~~~~~~
foo.cc:14:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%d",&c);
 ~~~~~^~~~~~~~~