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

int top, result[1000];

void push(int x){
    result[++top]=x;
}
int pop(){
    top--;
    return result[top+1];
}

int main(){
    int a,b;
    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;
}


