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

int top, 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;
}
