Swap and Sort

Shreyas recently became 5 star on codechef and is obsessed with sorting. He creates his own algorithm Shrey-Sort wherein he sorts the array in non decreasing order only by swapping with certain constraints as given below. In Shrey-Sort one can perform operations on the array. In each operation one can choose $i$ and $j$ and swap $a_i$ and $a_j$ only if $a_i+a_j$ is even. Operations can be perfo