import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N = I()

if N <= 2:
    print(N+1)
    exit()

for p in range(2,min(N,10**6+1)):
    r = 1
    while r <= N:
        if N % r == 0 and N//r <= p-1:
            print(p)
            exit()
        r *= p
        r += 1

ans = N-1
for d in range(1,int(N**.5)+1):
    if N % d == 0:
        if d < N//d-1:
            ans = min(ans,N//d-1)

print(ans)