Hey Guys,

I am trying to solve this problem [contest:260][problem:A](https://codeforces.net/contest/455/problem/A) tagged DP. I am getting runtime error for my submission in case of larger inputs.

n =int(input())
arr = [int(x) for x in input().split()]

freq = [0]*(n + 1)

for i in arr:
    freq[i] = freq[i] + 1

dic = {}
def dp(a):
    if a in dic:
        return dic[a]
    if(a==0):
        return 0
    if(a==1):
        return freq[1]
    res = max(dp(a-1), dp(a-2)+a*freq[a])
    dic[a] = res
    return res

print(dp(n))

Can anyone please explain what I am doing wrong, I am a beginner. Any help will be appreciated.