View Compilation Error

0_0_33755809_11288.cpp: In function 'int main()':
0_0_33755809_11288.cpp:12:29: error: 'swap' was not declared in this scope
         if(x1>x2) swap(x1,x2);
                             ^
0_0_33755809_11288.cpp:13:29: error: 'swap' was not declared in this scope
         if(y1>y2) swap(y1,y2);
                             ^
0_0_33755809_11288.cpp:14:29: error: 'swap' was not declared in this scope
         if(x3>x4) swap(x3,x4);
                             ^
0_0_33755809_11288.cpp:15:29: error: 'swap' was not declared in this scope
         if(y3>y4) swap(y3,y4);
                             ^
0_0_33755809_11288.cpp:16:32: error: 'max' was not declared in this scope
         double minx = max(x1,x3);
                                ^
0_0_33755809_11288.cpp:17:32: error: 'min' was not declared in this scope
         double maxx = min(x2,x4);
                                ^