Choosing a Programming Language for Interviews(blog.codingforinterviews.com)

     * Libraries for reading arbitrary size integers

     * and for computing with arbitrary size integers

     * Efficiently handling files larger than RAM

     * Error handling when the file is not as promised?

   with open('input') as fin, open('output', 'w') as fout:
       for line_num, line in enumerate(fin, 1):
           fout.write('{0}\n'.format(int(line) * line_num))

    #include <stdio.h>
    int main(void){
        unsigned int lineno=0;
        char line[1000];
        unsigned int number;

        while (fgets(line, 999, stdin)) {
            sscanf(line, "%u", &number);
            printf("%u\n", number * lineno++);
        }
        return(0);
    }