n = int(raw_input()) vis = [False for_ in xrange(n+1)] p, q = [], [] for i in xrange(2, n+1):    if vis[i]:        continue    p.append(i)    for j in xrange(i+i, n+1, i):        vis[j]=True for i in p:    cc, tmp=1, i    while tmp <= n:        cc += 1        tmp *= i    q.append(cc-1) lb, ub = n, n*n while ub - lb > 1:    mid = (lb + ub) / 2    flag = True      for (i, j) in zip(p, q):        if mid < 2 * (i**j):            flag = False            break    if flag:        ub = mid    else:        lb = mid print ub