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

int S[1000], top = 0;
void push(int);
int pop();
int main()
{
    int x, y, z;
    char s[100];

    while (scanf("%s", s) != EOF)
    {
        if (s[0] == '+')
        {
            push(pop() + pop());
        }
        else if (s[0] == '-')
        {
            x = pop();
            y = pop();
            push(y - x);
        }
        else if (s[0] == '*')
        {
            push(pop() * pop());
        }
        else
        {
            push(z = atoi(s));
        }
    }
    printf("%d\n", pop());

    return 0;
}
void push(int x)
{
    S[++top] = x;
}

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