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

int stack[100];
int count=0;

int pop()
{
  count--;
  return stack[count];
}

void push(int n)
{
  stack[count]=n;
  count++;
}

int main(void){
  int x,n,m;
  char s[100];
  
  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      n=pop();
      m=pop();
      push(n+m);
    } else if ( s[0] == '-' ){
      n=pop();
      m=pop();
      push(n-m);
    } else if ( s[0] == '*' ){
      n=pop();
      m=pop();
      push(n*m);
    } else {
      x = atoi(s);
      push(x);
    }
  }
  printf("%d\n",stack[count-1]);
  return 0;
}