Why will the following code not compile?

$```$

namespace ns$1$

$\{$

void print$()$;

void display$1()\{\}$;

$\}$

namespace ns$2$

$\{$

void print$()$;

void display $2()\{\}$;

$\}$

int main$()$

$\{$

using namespace ns$1$;

using namespace ns$2$;

display $1()$;

display $2()$;

print$()$;

return $0$;

$\}$

$```$

The call to print is ambiguous.

We have not included the iostream library.

We have not used namespace std$.$

It will compile.