#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int top, S[1000];
void push(int);
int pop();
int main(){
  int x,y;
  char s[100];
  top = 0;
  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      x=pop();
      y=pop();
      push(x+y);
    } else if ( s[0] == '-' ){
      y=pop();
      x=pop();
      push(x-y);
    } else if ( s[0] == '*' ){
      x=pop();
      y=pop();
      push(x*y);
    } else {
      push(atoi(s));
    }
  }
  printf("%d\n",pop());
  return 0;
}
void push(int x){
  top++;
  S[top]=x;
}
int pop(){
  top--;
  return S[top+1];
}

