AliceGameEasy | Topcoder Archive

Problem Statement

Alice and Kirito just played a game. The game consisted of a finite (possibly empty) sequence of turns. You do not know the exact number of turns. The turns were numbered starting from 1. In each turn, exactly one of our two players won. The winner of turn i scored i points.

You are given two longs x and y. Find out whether it is possible that at the end of the game Alice had exactly x points and Kirito had exactly y points. If it is possible, return the smallest number of turns Alice could have won. If the given final result is not possible, return -1 instead.

Definition

Class:: AliceGameEasy
Method:: findMinimumValue
Parameters:: long, long
Returns:: long
Method signature:: long findMinimumValue(long x, long y)
(be sure your method is public)

Constraints

x and y will be between 0 and 1,000,000,000,000(10^12), inclusive.

Examples

```
7
```
```
14
```
```
Returns: 2
```
This final result is possible. One possibility is that Alice won turns 1, 2, and 4 (for 1+2+4 = 7 points) and Kirito won turns 3, 5, and 6 (for 3+5+6 = 14 points). However, there are also some other possibilities in which Alice only won two of the six turns, so the correct answer is 2.
```
10
```
```
0
```
```
Returns: 4
```
There must have been four turns and Alice must have won all four of them.
```
932599670050
```
```
67400241741
```
```
Returns: 1047062
```
Watch out for integer overflow.
```
7
```
```
13
```
```
Returns: -1
```
```
0
```
```
0
```
```
Returns: 0
```
```
100000
```
```
400500
```
```
Returns: 106
```

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