1. An alphabet input system, comprising: a plurality of representative keys that is used to input first matched characters among alphabets; and combination keys that are input by combining any one of the plurality of representative keys and are used to generate combination characters which are alphabets except for the first characters, wherein the combination characters are pictographically derived from combinations of a combination symbol having a ‘reversed J’ shape as a combination key with a shape of the first character matching to each of the plurality of representative keys (here, the reversed J means a reversed shape of J), wherein the combination character includes a second character which is a character generated by sequentially inputting the representative key and the combination key, and a third character which is a character generated by sequentially inputting the combination key and the representative key, and wherein the first character includes ‘C’, ‘E’, ‘N’, ‘O’, ‘F’, ‘P’, ‘U’, ‘T’, ‘I’, ‘Y’, and ‘L’ among the alphabets, the second character includes ‘G’, ‘B’, ‘M’, ‘Q’, ‘A’, ‘R’, ‘W’, ‘S’, ‘H’, ‘K’, and ‘D’ among the alphabets, and the third character includes ‘J’, ‘X’, ‘V’, and ‘Z’ among the alphabets.