#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;
}
