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

#define STACK_SIZE 100  /* スタックデータ数の最大値 */

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

int main(void)
{
     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;
}
