There are $n$ cities and $m$ flight connections. Your task is to check if you can travel from any city to any other city using the available flights. \InputFile The first line has two integers $n$ and $m$: the number of cities and flights. The cities are numbered $1, 2, ..., n$. After this, there are $m$ lines describing the flights. Each line has two integers $a$ and $b$: there is a flight from city $a$ to city $b$. All flights are one-way flights. \OutputFile Print "\textbf{YES}" if all routes are possible, and "\textbf{NO}" otherwise. In the latter case also print two cities $a$ and $b$ such that you cannot travel from city $a$ to city $b$.