/* Stack */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int top, s[1000];

void push(int x)
{
    top++;
    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] == '-'){
            a = pop();
            b = pop();
            push(b-a);
        } else if(s[0] == '*'){
            a = pop();
            b = pop();
            push(a*b);
        } else{
            push(atoi(s));
        }
    }
    printf("%d\n", pop());
    return 0;
}
