Problem1133--数列问题

1133: 数列问题

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 376  Solved: 240
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Description

已知一个数列的前3个数为3,4,5,以后每个数为前3个数的和,编程序求此数列的第N项

Input

输入N(N<=35)

Output

求出第N项的值

Sample Input Copy

28

Sample Output Copy

25527448