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

int top,S[1000];

void push(int x){
	S[++top] = x;
	for(i = 1;i <= top; i++){
		printf("S[%d] = %d",i,S[i]);
		if(i != top){
			printf(" ");
		}
		else{
			printf("\n");
		}
	}
}

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] == '-'){
		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;
}