hdu 2046 骨牌铺方格

#include<stdio.h>
int main()
{
	_int64 ca[55] = {0,1,2};
	int i,n;
	for(i = 3; i <=50; i++)
		ca[i] = ca[i-1] + ca[i-2];
	while(~scanf("%d",&n))
		printf("%I64d\n",ca[n]);
	return 0;
}