fid     = fopen('input.txt','r');
sumX    = 0;
while 1
    str = fgetl(fid);
    if str==-1; break;end
    sumX = sumX + evalX(str);
end
fclose(fid);
disp(sumX)

% functions
function x = evalX(s)
s = strtrim(s);

if any(s=='(')
    % find innermost () and replace with val, then go recursive
    openIdx = find(s=='(');
    closeIdx = find(s==')');
    if length(openIdx)==1
        openIdxF  = openIdx;
        closeIdxF = closeIdx;
    else
        for k=1:length(openIdx)-1
            z=(closeIdx > openIdx(k)) & (closeIdx < openIdx(k+1));
            if any(z)
                openIdxF  = openIdx(k);
                closeIdxF = closeIdx(z);
                closeIdxF = closeIdxF(1);
                break
            end
            openIdxF = openIdx(end);
            closeIdxF = closeIdx(1);
        end
    end
    val = evalX(s(openIdxF+1:closeIdxF-1));
    val = evalX([s(1:openIdxF-1),num2str(val),s(closeIdx+1:end)]);
else
    y   = strsplit(s);
    for j=1:length(y)
        y{j}=[' ',y{j},' '];
    end

    if any(s=='+') && any(s=='*') % Only for Part 2
        % do additions first
        for k=1:length(y)
            if isequal(y{k},' + ')
                val = evalX([y{k-1},' ',y{k},' ',y{k+1}]);
                val = evalX( [cell2mat(y(1:k-2)),num2str(val),cell2mat(y(k+2:end))]);
                break
            end
        end

    else
        val = str2double(y{1});
        for i=2:2:length(y)-1
            val = eval([num2str(val),y{i},y{i+1}]);
        end
    end
end
x=val;
end