习题4-11 兔子繁衍问题（15 分）

#include

int main()
{

    int N,sum=1,now=0,increase=0,month=1;

    scanf("%d",&N);

    if(sum==N) printf("%d",month);
    else{

        month++;
        now=sum+increase;

        while(nowmonth++;
            increase=sum;
            sum=now;
            now=sum+increase; 

        }

        printf("%d",month);

    }

    return 0;

}