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

int top,S[100];

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

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


int main(void){

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

