#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;

}

