// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

console.log(solution('13000000000 DUP 4 POP 5 DUP + DUP + +'));
console.log(Number.MAX_VALUE);
function solution(S) {
    //split S
    var res = S.split(' ');
    var stack = []; // stack is now []
    /*stack.push(2);       // stack is now [2]
    stack.push(5);       // stack is now [2, 5]
    var i = stack.pop(); // stack is now [2]*/
    for (var i = 0; i < res.length; i++) {
        console.log(stack.toString());
        switch (res[i]) {
          case 'POP':
            if(stack.length==0){
              return -1;
            }else{
              stack.pop();
            }
            break;
          case 'DUP':
            if(stack.length==0){
              return -1;
            }else{
              // duplicate last value
              stack.push(stack[stack.length-1]);
            }
            break;
          case '-':
            if(stack.length<=1 || (stack[stack.length-2]>stack[stack.length-1])){
              return -1;
            }else{
              var firstLastValue = stack.pop();
              var secondLastValue = stack.pop();
              stack.push(firstLastValue-secondLastValue);
            }
            break;
          case '+':
            if(stack.length<=1){
              return -1;
            }else{
              var firstLastValue = stack.pop();
              var secondLastValue = stack.pop();
              stack.push(firstLastValue+secondLastValue);
            }
            break;
          default:
            // there is no 'long' in javascript.
            stack.push(parseInt(res[i]));
            break;
        }
    }
    return stack.pop();

}