View Compilation Error

0_0_15922890_4902.cpp: In function 'int zhuangkuang(int)':
0_0_15922890_4902.cpp:9:38: error: 'Fabs' was not declared in this scope
         if(x[i]==x[h]||Fabs(x[i]-x[h])==Fabs(i-h))
                                      ^