R Program to subtract two numbers

Program

a <- readline(prompt = "Enter first number:")
a <- as.integer(a)
b <- readline(prompt = "Enter second number:")
b <- as.integer(b)
sum = a + b
print(paste("Sum of two numbers is: ", sum))

Output

> a <- readline(prompt = "Enter first number:")
Enter first number:18
> a <- as.integer(a)
> b <- readline(prompt = "Enter second number:")
Enter second number:54
> b <- as.integer(b)
> sum = a + b
> print(paste("Sum of two numbers is: ", sum))
[1] "Sum of two numbers is:  72"