Executing program and pasting text into it (line by line)

Question

I have a script that seeks to execute a program, copy a line from a text file, and paste it into the program, then execute a 2nd instance of the program and copy the 2nd line from the text file and paste it into the 2nd instance of the program (continued for x amount of instances).

Simplified:

Execute 1st instance of program > copy 1st line from text file > paste 1st line into program > press button on program > execute 2nd instance of program > copy 2nd line from text file > paste 2nd line into program...

Here is what I have:

import os
import sys
from tkinter import Tk
import pyperclip
import pyautogui

list = int(input('How many instances of program to execute? (default: 50) '))
print(list)


f = open(r"Textfile.txt")
for line in f:
    strip = [line.strip() for line in f]
    print(strip)

for i in xrange(len(strip)):
    print(strip[i])

I tried (below) to combine executing the program and copying each line from the text file and pasting it into the instance of the program :

for i in range(list): 
    os.startfile(r'Program.exe')
    with open("Textfile.txt") as f:
        lines = f.readlines()
        lines = [l for l in lines if "ROW" in l]
        r = Tk()
        r.withdraw()
        r.clipboard_clear()
        r.clipboard_append(lines)
        pyperclip.paste()
    pyautogui.click(820, 270)

How do I make the script copy text (line by line) from a text file and paste it into each instance of the program being executed?

Thanks!