n=int(input())
a=list(map(int,input().split()))
d1=a[1]-a[0]
d2=a[1]/a[0]
f1=0
f2=0
for i in range(2,n):
    if ((a[i]-a[i-1])!=d1):
        f1=1
    if((a[i]/a[i-1])!=d2):
        f2=1
if(f1==0):
    print("dengcha")
elif(f2==0):
    print("dengbi")
else:
    print("no")
/**************************************************************
	Problem: 1806
	User: admin
	Language: Python
	Result: Accepted
	Time:235 ms
	Memory:34480 kb
****************************************************************/