What changes you can do in the header files to avoid the redefinition that compiler will give when both the header files are included in the same program keeping the declaration of both the functions same?

Content of h1.h
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h1.h
#include <iostream>
using namespace std;
int func(int a){
	cout<<"Multiplied by 2";
	return 2*a;
}
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Content of h2.h
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h2.h
#include <iostream>
using namespace std;
int func(int a){
	cout<<"divided by 2";
	return a/2;
}
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