foo.cc: In function 'void paixu()':
foo.cc:12:30: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
 if ((a[i]>a[j])||(a[i]==a[j])&&(b[i]>b[j]))
                  ~~~~~~~~~~~~^~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:25:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%ld %ld %ld",&n,&p,&m);
 ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:28:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%lf%lf",&a[i],&b[i]);
 ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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