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

void push(int x);
int pop();

int S[100]; 
int top=0;

int main(void)
{
	int a, b;
	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(b - a);
		}
		else if(s[0] == '*'){
			a = pop();
			b = pop();
			push(a*b);
		}
		else{
			push(atoi(s));
		}
	}
	
	printf("%d\n", pop());
	
	return 0;
}

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

int pop()
{
	top--;
	return S[top+1];
}
