(18 a) Suppose, you have two files named input1.txt and input2.txt" where each line of the files contains an integer number. Now, write a C program that reads the first line from both the input files, adds these values and writes the output to the output file named output.txt. Your program should follow the same procedure for the rest of lines of the input files until any one of the input files ends. Sample contents of Sample contents of Corresponding contents "input1.txt" input2.txt" "output.txt" 10 -5 5 2 10 12 5 -8 -3 1 21 18 : 9 -8 -3 11