foo.cc: In function 'Edge query(int, int, int, int, int)':
foo.cc:57:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     int mid = l + r >> 1;
               ~~^~~
foo.cc: In function 'int main()':
foo.cc:70:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~~
foo.cc:72:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld", &a[i]);
         ~~~~~^~~~~~~~~~~~~~~
foo.cc:78:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &op);
         ~~~~~^~~~~~~~~~~
foo.cc:81:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d %lld", &k, &v);
             ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:86:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d %d", &l, &r);
             ~~~~~^~~~~~~~~~~~~~~~~

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