#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(void){

	int a,b;
	char s[100];
	top = 0;
	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;

}



