#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", 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;
}
