//Using the Euclidian Algorithm
//Original program by John Hubbard from Schaum's Outline
//Programming in C++


#include<iostream.h>
void main()
{
	int m,n,r;
	cout<<"enter two positive numbers: "<<endl;
	cin>>m>>n;
	if(m<n)//This loop will insure that m>=n
	{//note the loop only goes into effect if m<n
		int temp=m;//we make the value of temp equal to m
		m=n;//we swap values between m and n
		n=temp;//now we swap values between n and temp
	}
	//Effectively, what we've done here is swap the values of m and n
	//only if m<n. The point here is to make sure that m is the larger of 	//the two no matter what order the 
	//user inputed the numbers.
	//**************************************************
	//Now we find the greatest common denominator
	cout<<"The greatest common denominator of "<<m<<" and "<<n<<" is ";
	while(n>0)//the loop continues as long as n>0, then it stops.
	{
		r=m%n;//r assumes the value of the modulus(remainder) of m 		//divided my n.
		m=n;//next we swap the values of m and n.
		n=r;//we turn n into the value of the remainder
	}//this process keeps looping through as long as n>0.
	cout<<m<<endl;//At this point m has reduced to the point of the GCD.
}