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

 int top;
 int 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] == '*' ){
        b = pop();
        a = pop();
        push(a*b);

    } else {
      push(atoi(s));

    }
  }
  
  printf("%d\n",pop());

  return 0;
}
