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

int top, s1[1000];
void push(int x)
{
    s1[++top] = x;
}
int pop()
{
    top--;
    return s1[top+1];
}
int main()
{
    int a, b;
    top = 0;
    char s[200];
    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(atoi(s));
        }
    }
    printf("%d\n",pop());
    return 0;
}