uva11063.cpp

#include <iostream>
#include <vector>
using namespace std;
int main(){
	int num=0, Case=1;
	while(cin>>num){
		vector<int>nums;
		bool right=true;
		for(int i=0;i<num;i++){
			int a;
			cin>>a;
			nums.push_back(a);
		}
		for(int i=0;i<num-1;i++){
			if(nums[i]>=nums[i+1]){
				right=false;
				break;
			}
		}
		if(right==true){
			for(int i=0;i<num;i++){
				for(int j=i;j<num;j++){
					for(int c=i;c<num;c++){
						if(c==i){
							if(j!=num-1){
								for(int d=j+1;d<num;d++){
									if(nums[i]+nums[j]==nums[c]+nums[d]){
										right=false;
										break;
									}
								}
							}else{
								continue;
							}
						}else{
							for(int d=c;d<num;d++){
								if(nums[i]+nums[j]==nums[c]+nums[d]){
									right=false;
									break;
								}
							}
						}
						if(right==false){
							break;
						}	
					}
					if(right==false){
						break;
					}
				}
				if(right==false){
					break;
				}
			}
		}
		if(right==false){
			cout<<"Case #"<<Case<<": It is not a B2-Sequence."<<endl;
		}else{
			cout<<"Case #"<<Case<<": It is a B2-Sequence."<<endl;
		}
		cout<<endl;
		Case++;
	}
}