#include <iostream>

using namespace std;

int nod(int array[])
{
    int var;
    for (int i = 1; i < array[0]; i++)
    {
        if ((array[0] % i == 0) && (array[1] % i == 0) && (array[2] % i == 0) && (array[3] % i == 0))
            var = i;
    }
    return var;
}

int main()
{
    int arr[4];
    for (int i = 0; i < 4; i++)
        cin >> arr[i];
    for(int i = 1; i < 4; ++i)
	{
		for(int j = 0; j < 4-i; j++)
		{
			if(arr[j] < arr[j+1])
			{
				int temp = arr[j];
				arr[j] = arr[j+1];
				arr[j+1] = temp;
			}
		}
	}
    cout << nod(arr);
}