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

int top, S[1000];

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

void push(int x){
  S[top + 1] = x;
  top++;
}

int main(){
  int a, b, x;
  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 {
      x = atoi(s);
      push(x);
    }
  }
  printf("%d\n", pop());

  return 0;
}
