#include<stdio.h>
#include<stdlib.h>
#include<string.h>
 
int main(){
    int x,y;
    char s[100];
    int stack[100];
    int num=0;
 
    while (scanf("%s", s) != EOF){
        if (s[0] == '+'){
            x = stack[--num];
            y = stack[--num];
            stack[num] = x + y;
            num++;
        }
        else if (s[0] == '-'){
            x = stack[--num];
            y = stack[--num];
            stack[num] = -x + y;
            num++;
 
        }
        else if (s[0] == '*'){
            x = stack[--num];
            y = stack[--num];
            stack[num] = x * y;
            num++;
 
        }
        else {
            x = atoi(s);
            stack[num] = x;
            num++;
        }
    }
    printf("%d\n",stack[--num]);
    return 0;
}