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

int top, S[1000];

void push(int x)
{
    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] == '-')
        {
            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;
}
