Extract information for date from other columns

I working with monthly data. Data is in a specific format in two columns Month and Year. Below you can see a sample of data:

df<-data.frame(
              Month=c("m1","m2","m3","m4","m5","m6","m7","m8","m9","m10","m11","m12"),
       Year=c("2020","2020","2020","2020","2020","2020","2020","2020","2020","2020","2020","2020"))

Now I want to convert this data, from that format into the format shown below or more precisely in column Date

So can anybody help me how to solve this problem?

>Solution :

In base R you can do:

df$Date <- as.Date(paste0(df$Year, gsub("m", "-", df$Month, fixed = TRUE), "-01"))