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$\centerline{{\it this is} {\bf this is} window}$\\

$\centerline{\large{afa.azad@gmail.com }}$\\

$\centerline{\LARGE{afasaddarsad.mihanblog.com }}$\\

\Huge{AfA}\\

${a+b} \over {b+c}$\\

$x^{x^{2y}}$\\

$x_{x^4}$\\

$x^{y^5_2}_{z^2_5}$\\

$a+1+\cdots +a+1$\\

$\sqrt[a+2]{x+y+z}$\\

$x={y^2\over k+1}$\\

${y^2\atop k+1}$\\

$x=\frac{y^2}{k+1}$\\

$a_0+{\frac{1}{a_1+{\frac{1}{a_2+1}}}}$\\

$\overline{\underline c+\overline d}$\\

$\overbrace{a+b+\underbrace{c+d}_8+e+f}^3$\\

$y_3^{\prime\prime\prime}$\\

$y_4''''''$\\

$a\times {(b\div c)}$\\

$\bigg({n \atop k}\bigg)$\\

$n\choose k$\\\\

$\sum_k^i n+1$\\

$\int_0^1 x^5$\\

$\begin{array}{cc}
a&b\\
c&d
\end{array}$\\\\

$\pmatrix{\begin{tabular}{c|c|c|c} 
${x_1}$ &  &  &  \\ 
${x_2}$ &  &  &  \\ 
$\vdots$ &A &$\cdots$ &0 \\
 & & & \\
${x_n}$ & & & \\ \hline
y &0 &A &$\vdots$ \\ \hline
 &0 &$\cdots$ &0 \\
\end{tabular}}$

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