杭电acm2046

#include <stdio.h>int main() {int n, i;__int64 a[50]={1, 2, 3};for(i=3; i<50; i++) {a[i] = a[i-1] + a[i-2];}while(~scanf("%d", &n)) {printf("%I64d\n", a[n-1]);}return 0;}