#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() {
    char s[1] = {};
    int a,b;
    top = 0;


    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;
}
