# Codeforces Round #596 (Div. 2, based on Technocup 2020 Elimination Round 2) A. Forgetting Things 水题

A. Forgetting Things

Kolya is very absent-minded. Today his math teacher asked him to solve a simple problem with the equation 𝑎+1=𝑏 with positive integers 𝑎 and 𝑏, but Kolya forgot the numbers 𝑎 and 𝑏. He does, however, remember that the first (leftmost) digit of 𝑎 was 𝑑𝑎, and the first (leftmost) digit of 𝑏 was 𝑑𝑏.

Can you reconstruct any equation 𝑎+1=𝑏 that satisfies this property? It may be possible that Kolya misremembers the digits, and there is no suitable equation, in which case report so.

## Input

The only line contains two space-separated digits 𝑑𝑎 and 𝑑𝑏 (1≤𝑑𝑎,𝑑𝑏≤9).

## Output

If there is no equation 𝑎+1=𝑏 with positive integers 𝑎 and 𝑏 such that the first digit of 𝑎 is 𝑑𝑎, and the first digit of 𝑏 is 𝑑𝑏, print a single number −1.

Otherwise, print any suitable 𝑎 and 𝑏 that both are positive and do not exceed 109. It is guaranteed that if a solution exists, there also exists a solution with both numbers not exceeding 109.

## Examples

input

1 2

output

199 200

## 题意

现在告诉你a+1=b，现在给你a和b的最高位，然后让你输出可能的a和b是什么，如果无解输出-1

## 题解

可能性就3种，其他都无解，枚举这种可能性就好。

## 代码

```
#include<iostream>
using namespace std;
int main(){
int a,b;
cin>>a>>b;
if(b==1&&a==9){
cout<<"9 10"<<endl;
}else if(b-a==1){
cout<<a<<" "<<b<<endl;
}else if(a==b){
cout<<a<<"1 "<<b<<"2"<<endl;
}else{
cout<<"-1"<<endl;
}
}
```