Problems
Windows
Windows
On the \textit{\textbf{Windows}} desktop, open N windows. Known coordinates of the upper-left corner of \textbf{x\[i\]}, \textbf{y\[i\]} as well as the width and height of each window \textbf{w\[i\]}, \textbf{h\[i\]} (\textbf{i=1..N}). How many windows are visible on the screen? The window is visible, if not completely covered with other windows open after him.
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\InputFile
In the line of the file is written pevoy one number \textbf{N} - the number of windows. In the next \textbf{N} lines of four numbers - \textbf{x\[i\]}, \textbf{y\[i\]}, \textbf{w\[i\]}, \textbf{h\[i\]} (\textbf{i = 1..N}). The procedure of opening the windows to their order corresponds to the input data. All values are natural and do not exceed \textbf{1000}.
\OutputFile
A single number - the number of visible windows on the screen.
Input example #1
4 5 3 2 5 2 4 6 2 1 3 3 7 3 1 6 6
Output example #1
3