foo.cc:1:22: warning: '#pragma GCC optimize' is not a string or number [-Wpragmas]
 #pragma GCC optimize(fast)
                      ^~~~
foo.cc: In function 'int main()':
foo.cc:41:29: warning: narrowing conversion of 'y[i]' from 'long long int' to 'double' inside { } [-Wnarrowing]
    b[++cnt]=(bian){i,i-1,y[i]};
                          ~~~^
foo.cc:48:38: warning: narrowing conversion of 'yy[i]' from 'long long int' to 'double' inside { } [-Wnarrowing]
    b[++cnt]=(bian){i+bas,i+bas-1,yy[i]};
                                  ~~~~^
foo.cc:75:9: warning: variable 'm1' set but not used [-Wunused-but-set-variable]
  double m1,m2;
         ^~
foo.cc:75:12: warning: variable 'm2' set but not used [-Wunused-but-set-variable]
  double m1,m2;
            ^~
foo.cc:76:6: warning: unused variable 'to1' [-Wunused-variable]
  int to1,to2;
      ^~~
foo.cc:76:10: warning: unused variable 'to2' [-Wunused-variable]
  int to1,to2;
          ^~~
foo.cc:35:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld%lld%lld%lld",&n,&m,&x,&xx);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:39:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld",&y[i]);
   ~~~~~^~~~~~~~~~~~~~
foo.cc:46:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld",&yy[i]);
   ~~~~~^~~~~~~~~~~~~~~

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