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- All Contests
- ProjectEuler+
- Project Euler #167: Investigating Ulam sequences

# Project Euler #167: Investigating Ulam sequences

# Project Euler #167: Investigating Ulam sequences

Contest ends in

_{This problem is a programming version of Problem 167 from projecteuler.net}

For two positive integers and , the Ulam sequence is defined by , and for , is the smallest integer greater than which can be written in exactly one way as the sum of two distinct previous members of .

For example, the sequence begins with

does not belong to it because has two representations as the sum of two previous members, likewise .

Find

**Input Format**

Two space-separated integers and are given on first line.

**Constraints**

**Output Format**

Print one integer which is the answer to the problem.

**Sample Input 0**

```
2 10
```

**Sample Output 0**

```
23
```

**Explanation 0**

Beginning of is