#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,a[110],i;
    cin>>n;
    for(i = 1;i <= n;i++){
    	cin>>a[i];
	}
	int x = a[2] - a[1];
	double y = a[2] * 1.0 / a[1];
	int dc = 1;
	int db = 1;
	for(i = 3;i <= n;i++){
		if(a[i]-a[i-1] != x){
			dc = 0;
		}
		
		if(a[i] * 1.0 / a[i-1] != y){
			db = 0;
		}
	}
	
	if(dc == 1) cout<<"dengcha";
	else if(db == 1) cout<<"dengbi";
	else cout<<"no";
    return 0;
}
/**************************************************************
	Problem: 1806
	User: admin
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/