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

#define N 1000
int top;
int S[N];

void push(int);

int pop();

int main(){
  int x,y;
  top = 0;
  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();
      push(x * y);
    }
    else{
      push(atoi(s));
    }
  }

  printf("%d\n",pop());

  return 0;
}

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

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

