foo.cc: In function 'int main()':
foo.cc:49:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   49 |  scanf("%d%d%d%d",&n,&m,&a,&b);//输入矩阵大小、感染源个数和领主个数
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:51:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   51 |   scanf("%d%d",&c[i],&d[i]);//输入感染源坐标
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~
foo.cc:56:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   56 |   scanf("%d%d",&e,&f);//输入领主坐标
      |   ~~~~~^~~~~~~~~~~~~~

Found 7 testcases.
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