View Compilation Error

0_0_8823719_14748.cpp: In function `int main()':
0_0_8823719_14748.cpp:20: error: call of overloaded `abs(double&)' is ambiguous
GCC/bin/../lib/gcc/mingw32/3.4.2/../../../../include/stdlib.h:363: note: candidates are: int abs(int)
GCC/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/cstdlib:153: note:                 long long int __gnu_cxx::abs(long long int)
GCC/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/cstdlib:123: note:                 long int std::abs(long int)