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


int S[1000];
int top;

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

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

int main(){
  top = 0;
  char s[100];
  int a,b;

  while(scanf("%s",s) != EOF){
    if(s[0] == '+'){
      b = pop();
      a = pop();
      push(a + b);
    }else if ( s[0] == '-' ){
      b = pop();
      a = pop();
      push(a - b);
    }else if ( s[0] == '*' ){
      b = pop();
      a = pop();
      push(a * b);
    }else {
      push(atoi(s));
    }
  }

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

