N이 1000000일때 1000000보다 큰 답안도 하나 준비해야함. import sys input = sys.stdin.readline N = int(input()) primes = [True] * 2000000 primes[0] = primes[1] = False for i in range(2,1001): if primes[i]: for j in range(i+i,2000000,i): primes[j] = False for i in range(N,2000000): if primes[i]: c_i = str(i) if c_i == c_i[::-1]: print(i) break