1 2 3 4 5 6 7 8 9 10
1 + 1 * 2 <=> 3 1 * 2 + 3 <=> 5 5 <=> 1 * 2 + 3 (1 + 2) * 3 <=> 9 //- -1 <=> 0 - 1 -1 + 2 <=> 1 -(1 + 2) <=> -3 1 + -1 <=> 0 2 * -1 <=> -2