"use strict";
function main(input) {

  const checkM = (num) => {
      if (1 <= num && num <= 12) {
          return true;
        } else {
            return false;
        }
    };

  const checkY = (num) => {
      if (1 <= num && num <= 99) {
          return true;
        } else {
            return false;
        }
    };

  const args = input.split("\n");
  const S = args[0];

  const first = parseInt(S.slice(0, 2));
  const second = parseInt(S.slice(2,4));

  let firstIsM = checkM(first);
  let firstIsY = checkY(first);

  let secondIsM = checkM(second);
  let secondIsY = checkY(second);

  if((firstIsY && secondIsM) && (firstIsM && secondIsY)) {
      console.log("AMBIGUOUS");
  } else if(firstIsY && secondIsM) {
      console.log("YYMM");
  } else if(firstIsM && secondIsY) {
      console.log('MMYY');
  } else {
      console.log('NA');
  }

}
main(require("fs").readFileSync("/dev/stdin", "utf8"));
