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

void push(int);
int pop(void);
int stack[100];
int stack_pointer = 0;

int main(){
    int x, a, b;
    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 {
            x = atoi(s);
            push(x);
        }
    }

    printf("%d", stack[stack_pointer]);
    return 0;
}

void push(int x){
    stack[stack_pointer] = x;
    stack_pointer++;
}

int pop(){
    return stack[stack_pointer];
    stack_pointer--;
}