#include <stdio.h>
#include <stdlib.h>

unsigned long long seed = 0x0f7b8b3c;

unsigned badrand() {
  seed = (seed * 16807) % 2147483647;
  return seed;
}

int main() {

  const char* basepair = "TAGC";

  for (int i = 0; i < 6000; i++)
    fputc(basepair[badrand() % 4],stdout);

  return 0;
}