## EMP - University Employees

On some island each inhabitant is either a knight who only tells the truth, or a liar who always lies. Also, on the island there exists a university of technology where some of the inhabitants work. All of the university employees will always tell you the following two things, no matter which employee you ask:

*N*employees who work more than me.

*M*employees of the university have a larger salary than me.

It is also known that no two employees of the university have an identical salary, and no two work equally. Write a program which will compute how many persons are employed by this university.

### Input

The only input line contains two integers *N* and *M*, with one space between them [*N, M* <= 1000000000].

### Output

The output must contain only one integer - the total number of employees of this university, or 0 if there is no way to find the number of employees.

### Example

Input:1 1Output:2

### Author: Filimonenkov D.O.

Added by: | Roman Sol |

Date: | 2006-04-24 |

Time limit: | 1s |

Source limit: | 50000B |

Memory limit: | 1536MB |

Cluster: | Cube (Intel G860) |

Languages: | All except: ERL JS-RHINO NODEJS PERL6 VB.NET |

Resource: | ZCon 2007 |