
#define _CRT_SECURE_NO_WARNINGS
#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;
}