I want to put the name of the people who have some value in some column.

mi df is:

```
name<-c("luis", "John", "Leo")
a1<-c("a","b",NA)
a2<-c("c",NA,"d")
a3<-c(NA,"d","e")

df<-data.frame(name,a1,a2,a3)

```

I want to get a result like this

```
a1: "Luis", "John"
a2: "Luis", "Leon"
a3: "John", "Leo" 

```