#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int top, INT[1000];
void push(int x)
{
    top++;
    INT[top] = x;
}
int pop()
{
  // if(top > 0)
        top--;
    return INT[top+1];
}
int main()
{
    int a,b;
    char s[100];
    top = 0;
    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;
}

