Output (does not change depending on arguments provided):
First string: SHELL=/bin/bash
Last string: _=./a.out

To test the time taken, we iterate over environ 10000 times

Time taken using copy (time ./a.out 10000)
real    0m1.715s
user    0m1.715s
sys     0m0.001s

Time taken using move (time ./a.out 10000 yes)
real    0m1.221s
user    0m1.220s
sys     0m0.001s

From these results, we observe that the move assignment is much faster than the
normal copy assignment.