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

int top,S[1000];

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

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


int main(){

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


while(scanf("%s",s) != -1){
	if(s[0] == '+'){
		a = pop();
		b = pop();
		push(a+b);
	}

	if(s[0] == '-'){
		a = pop();
		b = pop();
		push(b-a);
	}

	if(s[0] == '*'){
		a = pop();
		b = pop();
		push(a*b);
	}
	else push(atoi(s));
}
printf("%d\n",pop());

return 0;
}