#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int top,S[1000];


void push(int x){
    S[top+1] = x;
    top++;
}
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] == '-') {
            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;
}