View Compilation Error

0_0_36288640_5602.cpp: In function 'int main()':
0_0_36288640_5602.cpp:53:45: error: '__gcd' was not declared in this scope
                 add(i, j, i * j / __gcd(i ,j));
                                             ^
0_0_36288640_5602.cpp:56:30: error: 'sort' was not declared in this scope
         sort(e, e + edge, cmp);
                              ^