#include <stdio.h>

int top, a[10000];

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

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

int main()
{
    int a, b;
    top = 0;
    char s[1000];
    while (scanf("%s", s) != -1)
    {
        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;
}
