#!/usr/bin/env python3

def test(n, setsums):
    newsums = [s+n for s in setsums] + setsums + [n]
    if len(newsums) != len(set(newsums)):
        return False
    return newsums

def search(left, right, length, best, setsums, lor, w): #left to right
    if len(left + right) >= length:
        if sum(left + right) < best:
            #print left+right, sum(left+right)
            for i, n in enumerate(left+right):
                w[i] = n
            return sum(left + right)
        return best
    hole = length - len(left + right) - 1
    minsum = sum(left + right) + (hole*(hole+1))//2 + left[-1]*hole
    if lor:
        n = max(left[-1]+1, sum(right)-sum(left) + 1)
        bound = right[0] - hole
    else:
        n = left[-1] + hole + 1
        bound = best - minsum
        if len(right) > 0 and right[0] < bound:
            bound = right[0]
    while n < bound and n < best - minsum - (n-left[-1])*hole*lor:
        newsums = test(n, setsums)
        if newsums:
            best = search(left + [n]*lor,
                          [n]*(not lor) + right,
                          length, best, newsums, not lor, w)
        n += 1
    return best

def base(length, best):
    x = length//2 + length % 2
    n = (x + 1 - length%2) * (x-1) + 1
    n = 20
    w = [0]*length
    while n < best - (length-1)*length - n*(length-1):
        best = search([n], [], length, best, [n], False, w)
        n += 1
    return "".join(map(str, w)), best

print(base(7, 500)[0])