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

int main(void) {
  FILE * bc;
  int nc;
  char expresion[100];
  
  if ((bc = popen("bc", "w")) == NULL) {
    perror("popen");
    exit(1);
  }

  do
  {
    nc=read(STDIN_FILENO, expresion, sizeof(expresion));
    expresion[nc]='\n';
    fprintf(bc, "%s\n", expresion); fflush(bc);
  } while (strncmp(expresion, "quit", 4)!=0);

  pclose(bc);
  exit(0);
}