dlina = int(input())
chisla = input().split()
parnie = []
neparnie = []

for i in range(dlina):
    if int(chisla[i]) // 2 == int(chisla[i]) / 2:
        parnie.append(int(chisla[i]))

    else:
        neparnie.append(int(chisla[i]))



if len(parnie) > len(neparnie):
    for u in range(dlina):
        if int(chisla[u]) in neparnie:
            print(u + 1)

else:
    for u in range(dlina):
        if int(chisla[u]) in parnie:
            print(u + 1)