var solve = (exp) => {
    var stack = [];
    var expression = exp.split(" ");
    for(var j=0;j<expression.length;j++) {
        var key = expression[j];
        if(key.match(/\d/)) {
            stack.push(parseInt(key));
        } else if(key.match(/\w/)) {
            if(Object.keys(progData).includes(key)) {
                stack.push(progData[key]);
            } else {
                stack.push(key);
            }
        }
        switch(key) {
            case "+": // add
                var opItems = stack.splice(stack.length-2,2);
                var result = opItems[0]+opItems[1];
                stack.push(result);
            break;
            case "-": // subtract
                var opItems = stack.splice(stack.length-2,2);
                var result = opItems[0]-opItems[1];
                stack.push(result);
            break;
            case "*": // multiply
                var opItems = stack.splice(stack.length-2,2);
                var result = opItems[0]*opItems[1];
                stack.push(result);
            break;
            case "/": // divide
                var opItems = stack.splice(stack.length-2,2);
                var result = opItems[0]/opItems[1];
                stack.push(result);
            break;
        }
    }
    return stack;
};
module.exports = solve;