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

int top, S[1000];

void push(int x)
{
	S[++top] = x;
}

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


int main(void){
	int a, b, x;
	top = 0;
	char s[100];

  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
    	a = pop();
    	b = pop();
    	push(a+b);
    } else if ( s[0] == '-' ){
    	a = pop();
    	b = pop();
    	push(b-a);
    } else if ( s[0] == '*' ){
    	a = pop();
    	b = pop();
    	push(a*b);
    } else {
      x = atoi(s);
    	push(x);
    }
  }
	printf("%d\n", pop());

  return 0;
}
