171_G. Mysterious numbers - 2


Input

The only line of input contains three integers a1, a2, a3 (1 ≤ a1, a2, a3 ≤ 20), separated by spaces.

Output

Output a single integer.

Examples

Input

2 3 2


Output

5


Input

13 14 1


Output

14


Input

14 5 9


Output

464


Input

17 18 3


Output

53
```python
f = [0] * 22
f[0], f[1], idx = [int(x) for x in input().split()]
for i in range (2, 22) : f[i] = f[i - 1] + f[i - 2]
print(f[idx])
```