#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int top;
int array[1001];
//atoi 文字 から number


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


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





int main(){

  int a,b;
  top = 0;
  
  char s[101];
  
  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;
}

