#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;
}

