#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() {
 	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;
}
