#include <stdio.h>
#include <conio.h>
#include <alloc.h>
struct stack {
  int aa;
} *p;
int top;
void push(int a)
{
  (p+top)->aa=a; top++;
}
pop()
{
  int c;

  top--; c=(p+top)->aa;
  return c;
}

void comp(char c)
{
  int a,b,s,i;
  b=pop(); a=pop();
  switch (c) {
  case '+':
     a=a+b;
     break;
  case '-':
     a=a-b;
     break;
  case '*':
     a=a*b;
     break;
  case '/':
     a=a/b;
     break;
  case '^': // power
    for (s=i=1; i<=b; i++) s=s*a;
     a=s;
     break;
  }
  push(a);
}

void main()
{
  int n,aa,op1;
  char c,fg;

  printf("give me the number --> "); scanf("%d",&n);
  p=(struct stack *)malloc(sizeof(stack)*n); top=0; aa=0;
  printf("give me the postfix string --> ");
  while ((c=getche()) != '\r') {
    if ((c == '+') || (c == '-') || (c == '*') || (c == '/') || (c == '^')) {
       if (fg == 0) { push(aa); fg=1; aa=0; }
       comp(c);
    }
    if (c == ' ') {
      if (fg == 0) { push(aa); fg=1; aa=0; }
    }
    else
      if ((c >= '0') && (c <= '9')) { fg=0; aa=aa*10+c-'0'; }
  } /* while */
  op1=pop();
  printf("\nthe result ---> %d\n ",op1);
}