#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
const long long MOD = 1e9 + 7;
using namespace std;
bool isPrime(long long n) {
  if (n <= 1) return false;
  if (n <= 3) return true;
  if (n % 2 == 0 || n % 3 == 0) return false;
  for (long long i = 5; i * i <= n; i = i + 2)
    if (n % i == 0) return false;
  return true;
}
long long gcd(long long a, long long b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long lcm(long long a, long long b) {
  long long g = gcd(a, b);
  long long ans = (a * b) / g;
  return ans;
}
bool palindrome(string s) {
  for (long long i = 0; i < s.length() / 2; i++) {
    if (s[i] != s[s.length() - i - 1]) return 0;
  }
  return 1;
}
void printDivisors(int n) {
  for (int i = 1; i <= sqrt(n); i++) {
    if (n % i == 0) {
      if (n / i == i)
        printf("%d ", i);
      else
        printf("%d %d ", i, n / i);
    }
  }
}
int convert_number(string s) {
  int n;
  stringstream(s) >> n;
  return n;
}
vector<long long> prime;
void primes(long long m) {
  bool isprime[m];
  for (int i = 0; i <= m; i++) isprime[i] = true;
  for (int i = 3; i * i <= m; i++) {
    if (isprime[i]) {
      for (int j = i * i; j <= m; j += i) isprime[j] = false;
    }
  }
  prime.push_back(2);
  for (int i = 3; i <= m; i += 2)
    if (isprime[i]) prime.push_back(i);
}
bool sign(int n) {
  if (n > 0)
    return true;
  else
    return false;
}
int findsum(int n) {
  int sum = 0;
  if (n != 0)
    return sum = n + findsum(n - 1);
  else
    return 0;
}
int main(int argc, char *argv[]) {
  int h, m;
  char ch;
  cin >> h >> ch >> m;
  if (m < 59) m++;
  string s, ss;
  while (1) {
    if (m == 59) {
      if (h == 23)
        h = 0;
      else
        h++;
      m = 0;
    }
    s = to_string(m);
    if (s.size() == 1) s.insert(0, "0");
    ss = to_string(h);
    if (ss.size() == 1) ss.insert(0, "0");
    reverse((s).begin(), (s).end());
    if (s == ss) break;
    m++;
  }
  reverse((s).begin(), (s).end());
  cout << ss << ":" << s << '\n';
  return 0;
}
