foo.cc: In function 'int main()':
foo.cc:12:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d%d",&n,&m,&a,&b);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:16:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%1d",&x);
    ~~~~~^~~~~~~~~~
foo.cc:26:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (scanf("%d",&q);q--;) {
       ~~~~~^~~~~~~~~
foo.cc:30:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%1d",&x);
     ~~~~~^~~~~~~~~~

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