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

struct {int oper,span;  double val;} * expr;
char *pb;
int isz,ssz;

#define OI(i) (expr[i-1].span)

int compile(int c)  {
  int n,s,k,i;
  double x;
  char *p,*q,*qq, op[] = "+-*/";
  for (
    p = pb,  n = s = k = 0
  ; c!=EOF && c!='\n' && c!='\r'
  ; *p++ = c,  ++n,  c=getchar()
  )  {
    if (c==' ' || c=='\t')  s = 0;
    else  if (s==0)  {s = 1;  ++k;}
    if (n+1==isz)  {
      pb = realloc(pb,isz*=2);
      p = pb+n;
    }
  }
  *p = 0;   // a line just read, now parse & compile it
  if (ssz<k)  expr = realloc(expr,(ssz=k)*sizeof(*expr));
  for (i=n=0,p=pb; i<k; p=NULL,++i)  {
    q = strtok(p," \t");
    if (q[1]==0 && NULL!=(qq=strchr(op,*q)))  {
      if (n<2)  return -1;
      expr[i].oper = 1+(qq-op);
      expr[i].span = OI(OI(i));
      --n;
    }  else  if (x=strtod(q,&qq),qq==q+strlen(q))  {
      expr[i].val = x;
      expr[i].oper = 0;
      expr[i].span = i;
      ++n;
    }  else  return -1;
  }
  if (n>1)  return -1;
  return k;
}

cilk double eval(int n)  {
  double x,y;
  if (expr[n].oper==0)  return  expr[n].val;
  y = spawn eval(n-1);
  x = spawn eval(OI(n)-1);
  sync;
  switch (expr[n].oper)  {
    case 1: return x+y;
    case 2: return x-y;
    case 3: return x*y;
    case 4: return x/y;
  }
}

cilk int main()  {
  int c,k;
  double x;
  pb = malloc(isz=2);
  expr = malloc((ssz=1)*sizeof(*expr));
  while ((c=getchar())!=EOF)  {
    k = compile(c);
    if (k>0)  {
      x = spawn eval(k-1);  sync;
      printf("%f\n",x);
    }  else  if (k<0)  printf("error\n");
  }
  return 0;
}