#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(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;
}