All i want is to just click exacly span 1

Example let's go to youtube.com , then write something in searcher and finally click 1st span like this:

```
driver.Navigate().GoToUrl("https://youtube.com");
driver.FindElement(By.XPath("//*[@id='search']")).SendKeys("I should be so lucky");
driver.FindElement(By.XPath("//*[@id='search']")).SendKeys(Keys.Return);

```

And now i want click 1st link but this path : 

```
//*[@id="description-text"]/span

```

show us 19 links . How can i write span 1?
I try something liek this

```
//*[@id="description-text"]/span[1]

```

but this doesn't works.
Can somene heelp how to choose exacly only 1 span by changing this xpath?