#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;
}
