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

int top,S[1000];

void push(int);
int pop();

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

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