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

int top, S[1000];

void push(int x){
	/*top?????????????????????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) != 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;
}