Bob likes to draw camels: with a single hump, two humps, three humps, etc. He draws a camel by connecting points on a coordinate plane. Now he's drawing camels with *t* humps, representing them as polylines in the plane. Each polyline consists of *n* vertices with coordinates (*x*<sub class="lower-index">1</sub>, *y*<sub class="lower-index">1</sub>), (*x*<sub class="lower-index">2</sub>, *y*<sub class="lower-index">2</sub>), ..., (*x*<sub class="lower-index">*n*</sub>, *y*<sub class="lower-index">*n*</sub>). The first vertex has a coordinate *x*<sub class="lower-index">1</sub> = 1, the second — *x*<sub class="lower-index">2</sub> = 2, etc. Coordinates *y*<sub class="lower-index">*i*</sub> might be any, but should satisfy the following conditions:
 -  there should be *t* humps precisely, i.e. such indexes *j* (2 ≤ *j* ≤ *n* - 1), so that *y*<sub class="lower-index">*j* - 1</sub> &lt; *y*<sub class="lower-index">*j*</sub> &gt; *y*<sub class="lower-index">*j* + 1</sub>, -  there should be precisely *t* - 1 such indexes *j* (2 ≤ *j* ≤ *n* - 1), so that *y*<sub class="lower-index">*j* - 1</sub> &gt; *y*<sub class="lower-index">*j*</sub> &lt; *y*<sub class="lower-index">*j* + 1</sub>, -  no segment of a polyline should be parallel to the *Ox*-axis, -  all *y*<sub class="lower-index">*i*</sub> are integers between 1 and 4. 
For a series of his drawings of camels with *t* humps Bob wants to buy a notebook, but he doesn't know how many pages he will need. Output the amount of different polylines that can be drawn to represent camels with *t* humps for a given number *n*.
The first line contains a pair of integers *n* and *t* (3 ≤ *n* ≤ 20, 1 ≤ *t* ≤ 10).
6 1
6
4 2
0
3 1
14
3 2
0
3 3
0
3 10
0
4 1
22
4 3
0
4 9
0
5 1
16
5 2
70
5 3
0
5 5
0
5 9
0
5 10
0
6 1
6
6 2
232
6 3
0
6 4
0
6 10
0
19 1
0
19 2
0
19 3
1
19 4
32632
19 5
4594423
19 6
69183464
19 7
197939352
19 8
109824208
19 9
5846414
19 10
0
20 1
0
20 2
0
20 3
0
20 4
12628
20 5
3715462
20 6
96046590
20 7
468541040
20 8
503245466
20 9
90700276
20 10
0
import sys
input = sys.stdin.readline

n, t = map(int, input().split())
x = 16
y = 4
dp0 = [[0] * x for _ in range(1)]
for i in range(y):
    for j in range(y):
        if i < j:
            dp0[0][4 * i + j] = 1
for i in range(2, n):
    dp = [[0] * x for _ in range(i)]
    for j in range(i - 1):
        dpj = dp0[j]
        for k in range(y):
            for l in range(y):
                if not k ^ l:
                    continue
                dpkl = dpj[4 * k + l]
                for m in range(y):
                    if not l ^ m:
                        continue
                    if k < l > m or k > l < m:
                        dp[j + 1][4 * l + m] += dpkl
                    else:
                        dp[j][4 * l + m] += dpkl
    dp0 = [[dp[j][k] for k in range(x)] for j in range(i)]
if len(dp) <= 2 * t - 1:
    ans = 0
else:
    ans = sum(dp[2 * t - 1])
print(ans)