#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int top = 0,S[1000];


void push(int x) {
	S[top ++] = x;
}

int pop() {
	return S[--top];
}
 
int main(void) {
	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 ((a - b));
        }else if( s[0] == '*') {
            a = pop();
            b = pop();
            push ((a * b));
        }else{
            push(atoi(s));
        }
    }

    printf("%d\n",pop());

    return 0;
}