View Code of Problem 20

#include<stdio.h>
int main(){
	int i,n;
	int arr[100000] = {0};
	arr[1] = 1;
	arr[2] = 1;
	for(i=4 ; i < 100000; i*=2){
		arr[i] = 1;
	}
	for(i = 3;i < 100000; i ++){
		if(arr[i-1] == 0 || arr[i-2] == 0){
			arr[i] = 1;
		}else{
			arr[i] = 0;
		}
	}
	while(~scanf("%d",&n) != EOF){
		if(arr[n] == 1){
			printf("Yes\n");
		}else{
			printf("No\n");
		}
	}
	return 0;
}