xdoj-1109

#include<stdio.h>#define N 10007#define maxn 1000005int 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\n",dp[n]%N);}