618 B | 618 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
BLANK = " "
inp = input
# inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
n = ii()
ans = []
for a in range(2, n):
for b in range(a - 1, a + 1):
if n % (a + b) == 0 or (n - a) % (a + b) == 0:
ans.append((a, b))
p(f"{n}:")
for a, b in ans:
p(f"{a},{b}")
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()