#include <iostream>
#include <fstream>
using namespace std;
ifstream f("monotona.in");
ofstream g("monotona.out");
long long x,r,a,b,c,v;
int main()
{
    f>>x;
    r=x;
    x--;
    f>>a;
    while (x)
    {
        x--;
        f>>b;
        if (b>=a) c++;
        if (b<=a) v++;
        a=b;
    }
    if (c+1==r || v+1==r) g<<"da";
    else g<<"nu";
    return 0;
}