#include <stdio.h>
#include <string.h>
#include <math.h>

char *chsigns="+, -, *, /, max, min\n";

char *signs()
{
  return chsigns;
}

double oper(double a1, double a2, char *op)
{
  double res=0.0f;

/*  printf ("%f, %f, %s\n",a1,a2,op); */

  if (op[1] == 0)
  {
    switch (op[0])
    {
      case '+':
	res=a1+a2;
	break;
      case '-':
	res=a1-a2;
	break;
      case '*':
	res=a1*a2;
	break;
      case '/':
	if (a2 == 0.0f) op[0]=2; else res=a1/a2;
	break;
      default: /* BadExp */
	op[0]=1;
	return 0.0f;
    } /* switch */
    op[0]=0;
    return res;
  }

  if (strcmp(op,"max") == 0)
  {
    op[0]=0;
    return (a1 > a2) ? a1 : a2;
  }
  if (strcmp(op,"min") == 0)
  {
    op[0]=0;
    return (a1 < a2) ? a1 : a2;
  }

  op[0]=1;
  return 0.0f;
}