foo.cc: In function 'int main()':
foo.cc:66:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n); T = 2 * n + 1;
     ~~~~~^~~~~~~~~~
foo.cc:67:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i = 1; i <= n; ++i) scanf("%d%d", &xx1[i], &yy1[i]);
                                 ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:68:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i = 1; i <= n; ++i) scanf("%d%d", &xx2[i], &yy2[i]);
                                 ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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