foo.cc: In function 'int main()':
foo.cc:43:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d",&n,&m,&k);
  ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:47:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d",&x);
    ~~~~~^~~~~~~~~