Write a complete C$++$ program that does the following: It asks the user to enter a positive integer.

The program reads a value n entered by the user. If the value is not legal, the program terminates.

The program prints a table with n lines of output. On output line number x the program should list the numbers from $1$ to x together

with their sum.

Sample run of program:

Enter a positive integer: $7$

$1$ the sum is $1$

$12$ the sum is $3$

$123$ the sum is $6$

$1234$ the sum is $10$

$12345$ the sum is $15$

$123456$ the sum is $21$

$1234567$ the sum is $28$