driver.c

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>

int main() {
  FILE *pfin, *pfout;
  pfin = fdopen(3, "r");
  pfout = fdopen(4, "w");
  
  fprintf(pfout, "A\n");
  fflush(pfout);
  
  char x[10];
  fscanf(pfin, "%s", x);
  printf("%s\n", x);
  
  printf("\n");
  if(strcmp(x, "AA") == 0) {
    printf("0\n");
  } else {
    printf("1\n");
  }
  
  return 0;
}

driver.py

import os

os.write(4, 'A\n'.encode())

y = os.read(3, 16)
print(y)

print()
if y == b'AA\n':
  print(0)
else:
  print(1)

solution.py

x = input()
print(x*2)