Why is there a compile error when calling consturctor?

Question

class Normal {
private:
 int v1;
 int v2;
public:
 Normal()
{
 v1 = 0;
 v2 = 0;
}
 Normal (int m, int n); 
};

 Normal::Normal(int m = 5, int n = 5) 
{
 v1 = m;
 v2