Codeforces Round #361 (Div. 2) C. Mike and Chocolate Thieves

原题链接

C. Mike and Chocolate Thieves

time limit per test
2 seconds

memory limit per test
256 megabytes

input
standard input

output
standard output

Bad news came to Mike's village, some thieves stole a bunch of chocolates from the local factory! Horrible!

Aside from loving sweet things, thieves from this area are known to be very greedy. So after a thief takes his number of chocolates for himself, the next thief will take exactly k times
more than the previous one. The value of k (k > 1)
is a secret integer known only to them. It is also known that each thief's bag can carry at most n chocolates (if they intend to take
more, the deal is cancelled) and that there were exactly four thieves involved.

Sadly, only the thieves know the value of n, but rumours say that the numbers of ways they could have taken the chocolates (for a fixedn,
but not fixed k) is m.
Two ways are considered different if one of the thieves (they should be numbered in the order they take chocolates) took different number of chocolates in them.

Mike want to track the thieves down, so he wants to know what their bags are and value of n will help him in that. Please find the
smallest possible value of n or tell him that the rumors are false and there is no such n.

Input

The single line of input contains the integer m (1 ≤ m ≤ 1015) —
the number of ways the thieves might steal the chocolates, as rumours say.

Output

Print the only integer n — the maximum amount of chocolates that thieves' bags can carry. If there are more than one n satisfying
the rumors, print the smallest one.

If there is no such n for a false-rumoured m,
print  - 1.

Examples

input

1

output

8

input

8

output

54

input

10

output

-1

Note

In the first sample case the smallest n that leads to exactly one way of stealing chocolates is n = 8,
whereas the amounts of stealed chocolates are (1, 2, 4, 8) (the number of chocolates stolen by each of the thieves).

In the second sample case the smallest n that leads to exactly 8 ways
is n = 54 with the possibilities:(1, 2, 4, 8),  (1, 3, 9, 27),  (2, 4, 8, 16),  (2, 6, 18, 54),  (3, 6, 12, 24),  (4, 8, 16, 32),  (5, 10, 20, 40),  (6, 12, 24, 48).

There is no n leading to exactly 10 ways
of stealing chocolates in the third sample case.

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
ll n;
ll solve(ll m, ll &ans){

for(ll i = 2;; i++){
ll d = i * i * i;
if(d > m)
break;
ans += m / d;
}
if(ans >= n)
return true;
return false;
}
int main(){

// freopen("in.txt", "r", stdin);
ll l = 0, r = 1e18, ans;

scanf("%I64d", &n);
while(l < r){
ans = 0;
ll mid = (l + r) >> 1;
if(solve(mid, ans))
r = mid;
else
l = mid + 1;
}
ans = 0;
solve(l, ans);
if(ans == n)
printf("%I64d\n", l);
else
puts("-1");
return 0;
}