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

int S[1000], head;

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

void push(int x) {
    S[++head] = x;
}

int main() {
    int a, b;
    char s[100];
    head = 0;
    while(~scanf("%s", s)) {
        if(s[0] == '+') {
            a = pop();
            b = pop();
            push(a+b);
        } else if (s[0] == '-') {
            a = pop();
            b = 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;
}
