foo.cc: In function 'void sym::build(long long int, long long int, long long int)':
foo.cc:23:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   23 |   int mid= l+r >>1;
      |            ~^~
foo.cc: In function 'void sym::change(long long int, long long int, long long int)':
foo.cc:36:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   36 |   int mid=l(p)+r(p)>>1;
      |               ^
foo.cc: In function 'sym::Node sym::query(long long int, long long int, long long int)':
foo.cc:48:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   48 |   int mid=l(p)+r(p)>>1;
      |               ^
foo.cc: In function 'void sym::main()':
foo.cc:67:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   67 |   scanf("%lld%lld",&n,&m);int k,x,y;
      |   ~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:68:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   68 |   for(int i=1;i<=n;++i) scanf("%lld",&a[i]);
      |                         ~~~~~^~~~~~~~~~~~~~
foo.cc:71:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   71 |    scanf("%lld%lld%lld",&k,&x,&y);
      |    ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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