Write a program that will print a sentence to the screen 100 times.
Each time your program should make some "mistakes" by replacing
three random characters in the sentence by random letters.

For this problem you will need to be able to generate random numbers.

The C standard library has a function rand() that generates a random
integer between 0 and RAND_MAX.  Before using rand() you need to
initialize the random number generator by calling srand() with a seed.
A typical way to get a seed is to use the system clock.  

For more information on rand() and srand() type "man 3 rand" on the
unix prompt.  The code below shows an example program that generates
10 random numbers between 0 and 100:

#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>

main() {
  /* get time of day to use as a seed for the random number generator */
  struct timeval tp;
  if (gettimeofday(&tp, NULL) != 0) {
    printf("error getting time of day\n");
    exit(1);
  }

  /* initialize random number generator */
  srand((unsigned int)tp.tv_sec);

  /* print 10 random numbers between 0 and 100 */
  int i;
  for (i = 0; i < 10; i++) {
    int num = rand() % 100;
    printf("%d\n", num);
  }
}