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

int top, S[100];

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] == '-'){
            a = pop();
            b = pop();
            push(b-a);
        }else if(s[0] == '*'){
            a = pop();
            b = pop();
            push(a*b);
        }else push(atoi(s));
    }
printf("%d\n", pop());
        return 0;
}
