#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int top,S[1000];

void push(int x)//push x to stack
{
    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;
}
