hdu 2018 母牛的故事

#include<stdio.h>
int main(void)
{
    int i,n,j,k;
    long long narr[60];
    narr[1]=1;
    narr[2]=2;
    narr[3]=3;
    narr[4]=4;
    narr[5]=6;
    for(i=6; i<55; i++)
    {
        narr[i]=narr[i-1]+narr[i-3];
    }
    while(scanf("%d",&n)!=EOF,n)
    {
        printf("%lld\n",narr[n]);
    }
    return 0;
}