foo.cpp:1:1: error: 'include' does not name a type
 include <iostream>
 ^
foo.cpp: In function 'int main()':
foo.cpp:8:1: error: 'cin' was not declared in this scope
 cin >> n >> m >> k;
 ^
foo.cpp:17:34: error: 'swap' was not declared in this scope
                  swap (x[i], x[j]);
                                  ^
foo.cpp:37:1: error: 'cout' was not declared in this scope
 cout << max;
 ^