#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
int n, num, v[2500], r;
cout << "n= "; cin >> n;
for (int i = 0; i < n; i++)
{
cin >> num;
v[i] = num;
}
sort(v, v + n);
r = v[1] - v[0];
for (int i = 1; i < n; i++)
{
if (v[i] - v[i - 1] != r)
{
cout << "Nu" << endl;
return 0;
}
}
cout << "Da" << endl;
return 0;
}
