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

void push(int x);
int pop();

int top = 0, S[199];

int main() {

  int x,y;
  int type;
  char s[100];

  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();
    }
    else push(atoi(s));
  }

  printf("%d\n", pop());
  
  return 0;
}

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

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

