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

int top, S[1000];

int pop();
void push(int);

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] == '-' ) {
      a = pop();
      b = 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;
}

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

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