#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()
{
    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;
}
