#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int top, s[1000];

void push(int x)
{
    /*top?????????????????????????????????????????\*/
    s[++top] = x;
}

int pop() 
{
    top--;
    /*top??????????????????????´?????????????*/
    return s[top + 1];
    
}


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