#include <stdio.h>

int top, N[1000];

int pop(void);
void push(int);

int main()
{
  
  int x,y,i;
  char n[100];
  top = 0;
  
  while(scanf("%s",n) != EOF) {
   if(n[0] == '+') {
      x = pop();
      y = pop();
      push(x+y);
    }

    else if( n[0] == '-')  {
      y = pop();
      x = pop();
      push(x-y);
    }

    else if( n[0] == '*') {
      x = pop();
      y = pop();
      push(x*y);
    }

    else {
      push(atoi(n));
    }
    
  }
  
  printf("%d\n",pop());
  return 0;
  
}


void push(int a)
{
  N[++top] = a;
}

int pop()
{
  top--;
  return N[top+1];
}