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

int top = 0,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;
}
      
