View Compilation Error

0_0_33755663_15783.cpp: In function 'int main()':
0_0_33755663_15783.cpp:16:32: error: 'max' was not declared in this scope
         double minx = max(x1,x3);
                                ^
0_0_33755663_15783.cpp:17:32: error: 'min' was not declared in this scope
         double maxx = min(x2,x4);
                                ^