import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		FastReader sc = new FastReader();
		String s = sc.next();
		
		boolean isYYMM = isYYMM(s);
		boolean isMMYY = isMMYY(s);
		
		if (isYYMM && isMMYY) {
			System.out.println("AMBIGUOUS");
		} else if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		}
	}
	
	private static boolean isYYMM(String date) {
		int year = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int month = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	
	private static boolean isMMYY(String date) {
		int month = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int year = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	static class FastReader { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } 
  
        String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() { 
            String str = ""; 
            try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.StringTokenizer; StringTokenizer java.util public class Main {
	public static void main(String[] args) {
		FastReader sc = new FastReader();
		String s = sc.next();
		
		boolean isYYMM = isYYMM(s);
		boolean isMMYY = isMMYY(s);
		
		if (isYYMM && isMMYY) {
			System.out.println("AMBIGUOUS");
		} else if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		}
	}
	
	private static boolean isYYMM(String date) {
		int year = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int month = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	
	private static boolean isMMYY(String date) {
		int month = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int year = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	static class FastReader { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } 
  
        String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() { 
            String str = ""; 
            try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
} Main public static void main(String[] args) {
		FastReader sc = new FastReader();
		String s = sc.next();
		
		boolean isYYMM = isYYMM(s);
		boolean isMMYY = isMMYY(s);
		
		if (isYYMM && isMMYY) {
			System.out.println("AMBIGUOUS");
		} else if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		}
	} main {
		FastReader sc = new FastReader();
		String s = sc.next();
		
		boolean isYYMM = isYYMM(s);
		boolean isMMYY = isMMYY(s);
		
		if (isYYMM && isMMYY) {
			System.out.println("AMBIGUOUS");
		} else if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		}
	} FastReader sc = new FastReader(); sc new FastReader() String s = sc.next(); s sc.next() sc.next sc boolean isYYMM = isYYMM(s); isYYMM isYYMM(s) isYYMM s boolean isMMYY = isMMYY(s); isMMYY isMMYY(s) isMMYY s if (isYYMM && isMMYY) {
			System.out.println("AMBIGUOUS");
		} else if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		} isYYMM && isMMYY isYYMM isMMYY {
			System.out.println("AMBIGUOUS");
		} System.out.println("AMBIGUOUS") System.out.println System.out System System.out "AMBIGUOUS" if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		} isYYMM {
			System.out.println("YYMM");
		} System.out.println("YYMM") System.out.println System.out System System.out "YYMM" if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		} isMMYY {
			System.out.println("MMYY");
		} System.out.println("MMYY") System.out.println System.out System System.out "MMYY" {
			System.out.println("NA");
		} System.out.println("NA") System.out.println System.out System System.out "NA" String[] args args private static boolean isYYMM(String date) {
		int year = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int month = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	} isYYMM {
		int year = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int month = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	} int year = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0'); year (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0') (date.charAt(0) - '0') * 10 (date.charAt(0) - '0') date.charAt(0) date.charAt date 0 '0' 10 (date.charAt(1) - '0') date.charAt(1) date.charAt date 1 '0' int month = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0'); month (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0') (date.charAt(2) - '0') * 10 (date.charAt(2) - '0') date.charAt(2) date.charAt date 2 '0' 10 (date.charAt(3) - '0') date.charAt(3) date.charAt date 3 '0' return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12)); ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12)) (1 <= month) (0 <= year) && (year <= 99) && (1 <= month) && (month <=12) (0 <= year) 0 year (year <= 99) year 99 (1 <= month) 1 month (month <=12) month 12 String date date private static boolean isMMYY(String date) {
		int month = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int year = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	} isMMYY {
		int month = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int year = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	} int month = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0'); month (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0') (date.charAt(0) - '0') * 10 (date.charAt(0) - '0') date.charAt(0) date.charAt date 0 '0' 10 (date.charAt(1) - '0') date.charAt(1) date.charAt date 1 '0' int year = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0'); year (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0') (date.charAt(2) - '0') * 10 (date.charAt(2) - '0') date.charAt(2) date.charAt date 2 '0' 10 (date.charAt(3) - '0') date.charAt(3) date.charAt date 3 '0' return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12)); ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12)) (1 <= month) (0 <= year) && (year <= 99) && (1 <= month) && (month <=12) (0 <= year) 0 year (year <= 99) year 99 (1 <= month) 1 month (month <=12) month 12 String date date static class FastReader { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } 
  
        String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() { 
            String str = ""; 
            try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } FastReader BufferedReader br; br StringTokenizer st; st public FastReader() { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } FastReader { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } next { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } IOException  e { 
                    e.printStackTrace(); 
                } e.printStackTrace() e.printStackTrace e { 
                    st = new StringTokenizer(br.readLine()); 
                } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() { 
            return Integer.parseInt(next()); 
        } nextInt { 
            return Integer.parseInt(next()); 
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() { 
            return Long.parseLong(next()); 
        } nextLong { 
            return Long.parseLong(next()); 
        } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() { 
            return Double.parseDouble(next()); 
        } nextDouble { 
            return Double.parseDouble(next()); 
        } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine() { 
            String str = ""; 
            try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } nextLine { 
            String str = ""; 
            try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } String str = ""; str "" try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } IOException e { 
                e.printStackTrace(); 
            } e.printStackTrace() e.printStackTrace e { 
                str = br.readLine(); 
            } str = br.readLine() str br.readLine() br.readLine br return str; str public class Main {
	public static void main(String[] args) {
		FastReader sc = new FastReader();
		String s = sc.next();
		
		boolean isYYMM = isYYMM(s);
		boolean isMMYY = isMMYY(s);
		
		if (isYYMM && isMMYY) {
			System.out.println("AMBIGUOUS");
		} else if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		}
	}
	
	private static boolean isYYMM(String date) {
		int year = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int month = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	
	private static boolean isMMYY(String date) {
		int month = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int year = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	static class FastReader { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } 
  
        String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() { 
            String str = ""; 
            try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
} public class Main {
	public static void main(String[] args) {
		FastReader sc = new FastReader();
		String s = sc.next();
		
		boolean isYYMM = isYYMM(s);
		boolean isMMYY = isMMYY(s);
		
		if (isYYMM && isMMYY) {
			System.out.println("AMBIGUOUS");
		} else if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		}
	}
	
	private static boolean isYYMM(String date) {
		int year = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int month = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	
	private static boolean isMMYY(String date) {
		int month = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int year = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	static class FastReader { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } 
  
        String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() { 
            String str = ""; 
            try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		FastReader sc = new FastReader();
		String s = sc.next();
		
		boolean isYYMM = isYYMM(s);
		boolean isMMYY = isMMYY(s);
		
		if (isYYMM && isMMYY) {
			System.out.println("AMBIGUOUS");
		} else if (isYYMM) {
			System.out.println("YYMM");
		} else if (isMMYY) {
			System.out.println("MMYY");
		} else {
			System.out.println("NA");
		}
	}
	
	private static boolean isYYMM(String date) {
		int year = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int month = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	
	private static boolean isMMYY(String date) {
		int month = (date.charAt(0) - '0') * 10 + (date.charAt(1) - '0');
		int year = (date.charAt(2) - '0') * 10 + (date.charAt(3) - '0');
		
		return ((0 <= year) && (year <= 99) && (1 <= month) && (month <=12));
	}
	static class FastReader { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } 
  
        String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() { 
            String str = ""; 
            try{ 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
}
