#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: huanghengyi
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/