[C++]complex with int type

#include <complex>
#include <iostream>
using namespace std;
int main(void )
{
    complex< int> z(20, 200);
    cout << abs< int>(z) << endl;
    return 0;
}

According to the C++ ISO spec, §26.2/2:

The effect of instantiating the template complex for any type other than float, double or long double is unspecified.