Problem:
Score : 200 points

Problem Statement

You have a digit sequence S of length 4. You are wondering which of the following formats S is in:

YYMM format: the last two digits of the year and the two-digit representation of the month (example: 01 for January), concatenated in this order

MMYY format: the two-digit representation of the month and the last two digits of the year, concatenated in this order

If S is valid in only YYMM format, print YYMM; if S is valid in only MMYY format, print MMYY; if S is valid in both formats, print AMBIGUOUS; if S is valid in neither format, print NA.

Constraints

S is a digit sequence of length 4.

Input

Input is given from Standard Input in the following format:

S

Output

Print the specified string: YYMM, MMYY, AMBIGUOUS or NA.

Sample Input 1

1905

Sample Output 1

YYMM

May XX19 is a valid date, but 19 is not valid as a month. Thus, this string is only valid in YYMM format.

Sample Input 2

0112

Sample Output 2

AMBIGUOUS

Both December XX01 and January XX12 are valid dates. Thus, this string is valid in both formats.

Sample Input 3

1700

Sample Output 3

NA

Neither 0 nor 17 is valid as a month. Thus, this string is valid in neither format.

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>

#define REP(i,n) for(i=0;i<n;i++)

//prototype declaration
int iin();
long long llin();
double din();
char cin();
void stin(char *s);
void iout(int i);
void llout(long long i);
void dout(double i);
void cout(char c);
void stout(char *s);
int dfs(int v, int n, int *visited, int table[n][n]);
int gcd(int a, int b);
int lcm(int a, int b);
long long llgcd(long long a, long long b);
long long lllcm(long long a, long long b);

//main function
int main() {
    char s[4];
    stin(s);
    int a, b, c, d;
    a = s[0] - '0';
    b = s[1] - '0';
    c = s[2] - '0';
    d = s[3] - '0';
    if (a*10 + b == 0 || c*10 + d == 0) {
        stout("NA");
        return 0;
    }
    if (a*10 + b > 0 && a*10 + b < 13) {
        if (c*10 + d > 0 && c*10 + d < 13) {
            stout("AMBIGUOUS");
        } else {
            stout("MMYY");
        }
    } else {
        if (c*10 + d > 0 && c*10 + d < 13) {
            stout("YYMM");
        } else {
            stout("NA");
        }
    }
    return 0;
}

//body function
int iin() {
    int i;
    scanf("%d", &i);
    return i;
}

long long llin() {
    long long i;
    scanf("%lld", &i);
    return i;
}

double din() {
    double i;
    scanf("%lf", &i);
    return i;
}

char cin() {
    char c;
    scanf("%c", &c);
    return c;
}

void stin(char *s) {
    scanf("%s", s);
}

void iout(int i) {
    printf("%d\n", i);
}

void llout(long long i) {
    printf("%lld\n", i);
}

void dout(double i) {
    printf("%lf\n", i);
}

void cout(char c) {
    printf("%c\n", c);
}

void stout(char *s) {
    printf("%s\n", s);
}

int dfs(int v, int n, int *visited, int table[n][n]) {
    int all_visited = 1, i;

    REP(i,n) {
        if (!visited[i]) {
            all_visited = 0;
            break;
        }
    }

    if (all_visited) {
        return 1;
    }

    int count = 0;

    REP(i,n) {
        if (!table[v][i]) continue;
        if (visited[i]) continue;

        visited[i] = 1;
        count += dfs(i, n, visited, table);
        visited[i] = 0;
    }

    return count;
}

int gcd(int a, int b) {
    int r;

    if (a < b) {
        r = a;
        a = b;
        b = r;
    }

    r = a % b;
    while (r != 0) {
        a = b;
        b = r;
        r = a % b;
    }

    return b;
}

int lcm(int a, int b) {
    int r = llgcd(a, b);
    a /= r;
    return a * b;
}

long long llgcd(long long a, long long b) {
    long long r;

    if (a < b) {
        r = a;
        a = b;
        b = r;
    }

    r = a % b;
    while (r != 0) {
        a = b;
        b = r;
        r = a % b;
    }

    return b;
}

long long lllcm(long long a, long long b) {
    long long r = llgcd(a, b);
    a /= r;
    return a * b;
}