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0_0_20650444_21768.cpp: In function 'double fabs(double)':
0_0_20650444_21768.cpp:22:8: error: redefinition of 'double fabs(double)'
 double fabs(double d){return d<0?-d:d;}//特别注意写法，防止-0.00
        ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/cmath:44:0,
                 from 0_0_20650444_21768.cpp:4:
GCC4.9.2/x86_64-w64-mingw32/include/math.h:181:31: note: 'double fabs(double)' previously defined here
   __CRT_INLINE double __cdecl fabs (double x)
                               ^