foo.cc: In function 'int main()':
foo.cc:13:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~
foo.cc:15:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
       scanf("%d", &a[i]);//第i个弯道时间
       ~~~~~^~~~~~~~~~~~~
foo.cc:20:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
       scanf("%d%d%d", &x, &y, &b);
       ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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