View Code of Problem 23

    #include<stdio.h>
    int main(){
		int n,i;
    	long a[90];
    	a[0]=1,a[1]=2;
    	for(i=2;i<90;i++){
    		a[i]=a[i-1]+a[i-2];
    	}
    	while(scanf("%d",&n)!=EOF&&n!=0){
    		printf("%lld\n",a[n-1]);
    	}
    }