Buggy python submission (verdict: Time Limit Exceeded):
# ABC161D
def f(k):
    if 1 <= k <= 9:
        print(k)
    nxt = [[0,1], [0,1,2], [1,2,3], [2,3,4], [3,4,5], [4,5,6], [5,6,7], [6,7,8], [7,8,9], [8,9]]
    cum_npi = [0, 9, 35, 110, 327, 956, 2782, 8089, 23527, 68468, 199368]
    for length, begin in enumerate(cum_npi):
        if k < begin:
            found = cum_npi[length - 1]
            break
    begin = 10 ** (length - 1)
    length, begin, found
    k -= found
    x = [[]] * (length + 1)
    x[1] = list(range(1, 10))
    x

    terminate = False
    i = 1
    while True:
        #print(f"a) i = {i}  x = {x}")
        if len(x[i]): # len(x[i])
            digit = x[i][0]
            if i < length: # i, length
                i += 1
                x[i] = nxt[digit].copy()
                #print(f"x) digit = {digit}  nxt[digit] = {nxt[digit]}  i = {i}  x[i] = {x[i]}")
                #print(f"b) i = {i}  x = {x}")
                if i == length: # i, length
                    while len(x[i]): # i, x[i]
                        k -= 1
                        #print(f"c) i = {i}  x = {x}, k = {k}")
                        if k == 0:
                            x.pop(0)
                            #print("answer =", x)
                            ans = "".join([str(j.pop(0)) for j in x])
                            print(ans)
                            terminate = True
                            break
                        else:
                            x[i].pop(0)
                        #print(f"d) i = {i}  x = {x}")
                    else:
                        #print(f"e) i = {i}  x = {x}")
                        while len(x[i]) == 0:
                            i -= 1
                            x[i].pop(0)
                    if terminate:
                        break

f(int(input()))


Fixed submission:
# ABC161D
def f(k):
    if 1 <= k <= 9:
        print(k)
    else:
        nxt = [[0,1], [0,1,2], [1,2,3], [2,3,4], [3,4,5], [4,5,6], [5,6,7], [6,7,8], [7,8,9], [8,9]]
        cum_npi = [0, 9, 35, 110, 327, 956, 2782, 8089, 23527, 68468, 199368]
        for length, begin in enumerate(cum_npi):
            if k < begin:
                found = cum_npi[length - 1]
                break
        begin = 10 ** (length - 1)
        length, begin, found
        k -= found
        x = [[]] * (length + 1)
        x[1] = list(range(1, 10))
        x

        terminate = False
        i = 1
        while True:
            #print(f"a) i = {i}  x = {x}")
            if len(x[i]): # len(x[i])
                digit = x[i][0]
                if i < length: # i, length
                    i += 1
                    x[i] = nxt[digit].copy()
                    #print(f"x) digit = {digit}  nxt[digit] = {nxt[digit]}  i = {i}  x[i] = {x[i]}")
                    #print(f"b) i = {i}  x = {x}")
                    if i == length: # i, length
                        while len(x[i]): # i, x[i]
                            k -= 1
                            #print(f"c) i = {i}  x = {x}, k = {k}")
                            if k == 0:
                                x.pop(0)
                                #print("answer =", x)
                                ans = "".join([str(j.pop(0)) for j in x])
                                print(ans)
                                terminate = True
                                break
                            else:
                                x[i].pop(0)
                            #print(f"d) i = {i}  x = {x}")
                        else:
                            #print(f"e) i = {i}  x = {x}")
                            while len(x[i]) == 0:
                                i -= 1
                                x[i].pop(0)
                        if terminate:
                            break

f(int(input()))

Buggy python submission (verdict: Runtime Error):
def f(k):
    def lunlun(n):
        s = [int(i) for i in str(n)]
        for i in range(len(s) - 1):
            if abs(s[i] - s[i + 1]) > 1:
                return False
        return True
    cum_npi = [0, 9, 35, 110, 327, 956, 2782, 8089, 23527, 68468, 199368]
    for i, begin in enumerate(cum_npi):
        if k < begin:
            begin = cum_npi[i-1]
            break
    print(f"begin = {begin}")
    found = begin
    while found != k:
        begin += 1
        if lunlun(begin):
            found += 1
            if found == k:
                break
    print(begin)

f(int(input()))


Fixed submission:
# ABC161D
def f(k):
    if 1 <= k <= 9:
        print(k)
    else:
        nxt = [[0,1], [0,1,2], [1,2,3], [2,3,4], [3,4,5], [4,5,6], [5,6,7], [6,7,8], [7,8,9], [8,9]]
        cum_npi = [0, 9, 35, 110, 327, 956, 2782, 8089, 23527, 68468, 199368]
        for length, begin in enumerate(cum_npi):
            if k < begin:
                found = cum_npi[length - 1]
                break
        begin = 10 ** (length - 1)
        length, begin, found
        k -= found
        x = [[]] * (length + 1)
        x[1] = list(range(1, 10))
        x

        terminate = False
        i = 1
        while True:
            #print(f"a) i = {i}  x = {x}")
            if len(x[i]): # len(x[i])
                digit = x[i][0]
                if i < length: # i, length
                    i += 1
                    x[i] = nxt[digit].copy()
                    #print(f"x) digit = {digit}  nxt[digit] = {nxt[digit]}  i = {i}  x[i] = {x[i]}")
                    #print(f"b) i = {i}  x = {x}")
                    if i == length: # i, length
                        while len(x[i]): # i, x[i]
                            k -= 1
                            #print(f"c) i = {i}  x = {x}, k = {k}")
                            if k == 0:
                                x.pop(0)
                                #print("answer =", x)
                                ans = "".join([str(j.pop(0)) for j in x])
                                print(ans)
                                terminate = True
                                break
                            else:
                                x[i].pop(0)
                            #print(f"d) i = {i}  x = {x}")
                        else:
                            #print(f"e) i = {i}  x = {x}")
                            while len(x[i]) == 0:
                                i -= 1
                                x[i].pop(0)
                        if terminate:
                            break

f(int(input()))

Buggy python submission (verdict: Time Limit Exceeded):
def f(k):
    def lunlun(n):
        s = [int(i) for i in str(n)]
        for i in range(len(s) - 1):
            if abs(s[i] - s[i + 1]) > 1:
                return False
        return True
    i = 0
    while k > 0:
        i += 1
        if lunlun(i):
            k -= 1
    print(i)

f(int(input()))

Fixed submission:
# ABC161D
def f(k):
    if 1 <= k <= 9:
        print(k)
    else:
        nxt = [[0,1], [0,1,2], [1,2,3], [2,3,4], [3,4,5], [4,5,6], [5,6,7], [6,7,8], [7,8,9], [8,9]]
        cum_npi = [0, 9, 35, 110, 327, 956, 2782, 8089, 23527, 68468, 199368]
        for length, begin in enumerate(cum_npi):
            if k < begin:
                found = cum_npi[length - 1]
                break
        begin = 10 ** (length - 1)
        length, begin, found
        k -= found
        x = [[]] * (length + 1)
        x[1] = list(range(1, 10))
        x

        terminate = False
        i = 1
        while True:
            #print(f"a) i = {i}  x = {x}")
            if len(x[i]): # len(x[i])
                digit = x[i][0]
                if i < length: # i, length
                    i += 1
                    x[i] = nxt[digit].copy()
                    #print(f"x) digit = {digit}  nxt[digit] = {nxt[digit]}  i = {i}  x[i] = {x[i]}")
                    #print(f"b) i = {i}  x = {x}")
                    if i == length: # i, length
                        while len(x[i]): # i, x[i]
                            k -= 1
                            #print(f"c) i = {i}  x = {x}, k = {k}")
                            if k == 0:
                                x.pop(0)
                                #print("answer =", x)
                                ans = "".join([str(j.pop(0)) for j in x])
                                print(ans)
                                terminate = True
                                break
                            else:
                                x[i].pop(0)
                            #print(f"d) i = {i}  x = {x}")
                        else:
                            #print(f"e) i = {i}  x = {x}")
                            while len(x[i]) == 0:
                                i -= 1
                                x[i].pop(0)
                        if terminate:
                            break

f(int(input()))

Buggy python submission (verdict: Runtime Error):
def f(k):
    def lunlun(n):
        s = [int(i) for i in str(n)]
        for i in range(len(s) - 1):
            if abs(s[i] - s[i + 1]) > 1:
                return False
        return True
    i = 0
    while k > 0:
        i += 1
        if lunlun(i):
            k -= 1
    print(i)

f(int(input())


Fixed submission:
# ABC161D
def f(k):
    if 1 <= k <= 9:
        print(k)
    else:
        nxt = [[0,1], [0,1,2], [1,2,3], [2,3,4], [3,4,5], [4,5,6], [5,6,7], [6,7,8], [7,8,9], [8,9]]
        cum_npi = [0, 9, 35, 110, 327, 956, 2782, 8089, 23527, 68468, 199368]
        for length, begin in enumerate(cum_npi):
            if k < begin:
                found = cum_npi[length - 1]
                break
        begin = 10 ** (length - 1)
        length, begin, found
        k -= found
        x = [[]] * (length + 1)
        x[1] = list(range(1, 10))
        x

        terminate = False
        i = 1
        while True:
            #print(f"a) i = {i}  x = {x}")
            if len(x[i]): # len(x[i])
                digit = x[i][0]
                if i < length: # i, length
                    i += 1
                    x[i] = nxt[digit].copy()
                    #print(f"x) digit = {digit}  nxt[digit] = {nxt[digit]}  i = {i}  x[i] = {x[i]}")
                    #print(f"b) i = {i}  x = {x}")
                    if i == length: # i, length
                        while len(x[i]): # i, x[i]
                            k -= 1
                            #print(f"c) i = {i}  x = {x}, k = {k}")
                            if k == 0:
                                x.pop(0)
                                #print("answer =", x)
                                ans = "".join([str(j.pop(0)) for j in x])
                                print(ans)
                                terminate = True
                                break
                            else:
                                x[i].pop(0)
                            #print(f"d) i = {i}  x = {x}")
                        else:
                            #print(f"e) i = {i}  x = {x}")
                            while len(x[i]) == 0:
                                i -= 1
                                x[i].pop(0)
                        if terminate:
                            break

f(int(input()))