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

int top,S[1000];

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


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] == '-'){
			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;
}

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

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

