#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;
}