#include <cstdio>

using namespace std;

int main(){
    freopen("bitona.in","r",stdin);
    freopen("bitona.out","w",stdout);

    int n,a,i=2,cat,ul,b,dir,primul;
    scanf("%d%d",&n,&a);

    cat=0;
    primul=a;
    ul=0;

    while(i<=n&&cat<4){
        scanf("%d",&b);

        dir=a<b?1:a>b?-1:0;

        if(dir!=ul&&dir!=0){
            cat++;
            ul=dir;
        }

        a=b;
        ++i;
    }

    if(cat==3){
        if((ul==1&&b>primul)||(ul==-1&&b<primul)){
        printf("NU\n");
        return 0;
        }
    }

    if(cat<4){
        printf("DA\n");
        return 0;
    }

    printf("NU\n");

    return 0;
}