Gears

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Time limit1sMemory limit1024 MB

Summary

Count how many distinct fractions a/b exist with both a and b in the range M to N.

Level: Medium5 of 10
Topics: Math, Number theory, Combinatorics, Brute force
Solved: No attempts yet

Problem

A watchmaker owns a lathe that can make gears with anywhere from $M$ to $N$ teeth.

Write a program that determines how many different gear ratios (transmissions built from two gears) can be produced on this machine. Two gear ratios are counted as different when their value — the number of teeth on the first gear divided by the number of teeth on the second gear — is different.

Input

The first line contains two space-separated integers $M$ and $N$ ( $1 \le M \le N \le 1000$ ), the minimum and maximum number of teeth on the gears that this machine can make.

Output

Print the number of different gear ratios that can be produced, on a single line.

Examples1

Example 1
Input
```
2 6
```
Expected output
```
17
```