import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
inf = 10**16
# md = 998244353
md = 10**9+7

def solve():
    for p in range(2,n+1):
        if p**2>n:break
        c=n
        a0=n%p
        while c:
            c,a=divmod(c,p)
            if a!=a0:break
        else:
            return p

    dd0=[]
    dd1=[]
    for d in range(1,n+1):
        if d*d>n:break
        if n%d:continue
        dd0.append(d)
        dd1.append(n//d)
    for d0,d1 in zip(dd0[::-1],dd1[::-1]):
        if d1-d0>=2:
            return d1-1

    return n

n=II()
print(solve())