What is the output of the following code :

#include

using namespace std;

int main ()

{

int firstvalue = 5, secondvalue = 15;

int * p1, * p2;

p1 = &firstvalue;

p2 = &secondvalue;

*p1 = 10;

*p2 = *p1;

p1 = p2;

*p1 = 20;

cout << "firstvalue is " << firstvalue << ' ';

cout << "secondvalue is " << secondvalue << ' ';

return 0;

}