//example1-2
#include <iostream.h>
double grav(double m1,double m2,double distance)
{
	double g,G=6.67259e-11;
	g=G*m1*m2/(distance*distance);
	return g;
}
void main()
{
	double g,Msun=1.987e30,Mearth=5.975e24;
	g=grav(Msun,Mearth,1.495e11);
	cout<<"The gravitation between sun and earth is "<<g<<"N."<<endl;
}