Congruency and eigen values $If$ $two$ $matrices$ $are$ $congruent$ $then$ $they$ $have$ $the$ $same$ $eigen$ $values$ $??$ I have tried solving it using definition of congruent matrices taking eigen value but didn't come up with a proper solution ... how to solve it ???

It is wrong $\pmatrix{0&1\cr1&0\cr}$ and $\pmatrix{2&1\cr0&-1/2\cr}$ are congruent but the first one has $1$ and $-1$ as eigen values and the second one has $2$ and $-1/2$ as eigen values.