XDU 1109

#include<stdio.h>
#define N 10007
#define maxn 1000005
int dp[maxn];
int main()
{
    dp[1]=1,dp[2]=2,dp[3]=4;
    for(int i=4;i<maxn;i++)
        dp[i]=dp[i-1]%N+dp[i-2]%N+dp[i-3]%N;
    int n;
    while(scanf("%d",&n)!=EOF)
        printf("%d
",dp[n]%N);
}