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8846번: Wymiana żarówki ↗

Solutions

Python 3
507 B | 507 chars
import sys
from math import sqrt, pi, sin, factorial
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = " " : [*map(int,inp().split(x))]
mfi = lambda x = " " : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print


def solve():
  n = ii()
  crt = 1
  
  sm = 1
  MOD = 500000009
  
  for i in range(2, n + 1):
    crt = (crt * 4) % MOD
    sm = (sm + crt) % MOD
  p(sm)

if __name__ == "__main__":
  tc = 1

  for t in range(1, tc+1):
    ret = solve()