思考：这道题考验的是罗辑思维，这个网址http://blog.csdn.net/sxhelijian/article/details/42609353的罗辑思维值得学习

#include
     
      int main(){    int n;    char d;    int f1,f2,f3,fn;    while(scanf("%d%c",&n,&d)!=EOF)    {        f1=1;        f2=2;        f3=3;        if(n==0)            break;        if(n==1)            printf("%d\n",f1);        else if(n==2)            printf("%d\n",f2);        else if(n==3)            printf("%d\n",f3);        else        {            for(int i=4;i<=n;i++)            {                fn=f3+f1;                f1=f2;                f2=f3;                f3=fn;            }            printf("%d\n",fn);        }                }}