function parseMolecule(formula) {
    // do your science here
    let result = [];
    while ((formula = parseNextChar(formula)) != '');
    function parseNextChar(str) {
        const elem = /^[A-Z]{1}[a-z]?/;
        const open = /^[({[]/;
        const close = /^[)}\]]/;
        const digit = /^[0-9]+/;
        let match;
        if (match = str.match(elem)) { // element - add object on stack
            const obj = {};
            Object.defineProperty(obj, match[0], {
                value: 1,
                enumerable: true,
                writable: true
            });
            result.push(obj);
        }
        else if (match = str.match(open)) { // opening brace - add '(' to stack
            result.push('(');
        }
        else if (match = str.match(close)) {              // closing brace - merge objects backwards
            const bracketStart = result.lastIndexOf('('); // to the opening brace
            const toMerge = result.slice(bracketStart + 1);
            const mergedObj = reduceChunk(toMerge);
            result.splice(bracketStart, result.length, mergedObj);
        }
        else if (match = str.match(digit)) { // digit - multiply last object
            const multed = multObject(result[result.length - 1], match[0]);
            result.splice(result.length - 1, 1, multed);
        }
        return str = str.substr(match[0].length);
    }
    function mergeObjects(obj1, obj2) {      // helpler - merge 2 objects adding missing keys
        Object.keys(obj1).forEach(key => {   // and summing values of matching keys
            if (obj2.hasOwnProperty(key)) {
                obj2[key] += obj1[key];
            }
            else {
                Object.defineProperty(obj2, key, {
                    value: obj1[key],
                    enumerable: true,
                    writable: true
                });
            }
        });
        return obj2;
    }
    function multObject(obj, mult) {       // helper - multiply values
        Object.keys(obj).forEach(key => {  // of all the keys of object
            obj[key] *= mult;
        });
        return obj;
    }
    function reduceChunk(array) {          // helper - merge all objects of array
        return array.reduce(mergeObjects);
    }
    return reduceChunk(result);
}