View Compilation Error

0_0_28150781_2658.cpp: In function 'int main()':
0_0_28150781_2658.cpp:23:21: error: 'max' was not declared in this scope
         x1=max(x1,x3);
                     ^
0_0_28150781_2658.cpp:25:21: error: 'min' was not declared in this scope
         x2=min(x2,x4);
                     ^