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

//using namespace std;



void push(int x){
	//top += 1;
	S[++top] = x;
}

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



int main(){
	int top, S[1000];
	char s[100];
	top = 0;
	//initialize;
	int a,b;
	while(scanf("%s",s) != EOF){

		//cout << "hoge" << endl;
		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));
		}
	}
	//cout << "hahah" << endl;

	printf("%d\n",pop());

	return 0;


}