$6.$ Prove that the following algorithm for finding the GCD of two integers m and n is incorrect.

int gcd $=1$;

for $($int k $=$ Math.min$($Math$.$sqrt$($n$),$ Math.sqrt$($m$)$; k $>=1$; k$--)\{$

if $($m$\%$k $==0$ && n$\%$k $==0)\{$

gcd $=$ k;

break;

$\}$

$\}$