#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)),x.end())
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define show(x) cerr<<#x<<" = "<<x<<endl;
#define PQ(T) priority_queue<T,v(T),greater<T> >
#define bn(x) ((1<<x)-1)
#define dup(x,y) (((x)+(y)-1)/(y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef tuple<int,int,int> T;
typedef vector<int> vi;
typedef vector<vi> vvi;
// typedef vector<ll> vl;
typedef vector<P> vp;
// typedef vector<T> vt;
int getInt(){int x;scanf("%d",&x);return x;}
template<typename T>istream& operator>>(istream&i,v(T)&v){rep(j,sz(v))i>>v[j];return i;}
template<typename T>string join(const v(T)&v){stringstream s;rep(i,sz(v))s<<' '<<v[i];return s.str().substr(1);}
template<typename T>ostream& operator<<(ostream&o,const v(T)&v){if(sz(v))o<<join(v);return o;}
template<typename T1,typename T2>istream& operator>>(istream&i,pair<T1,T2>&v){return i>>v.fi>>v.se;}
template<typename T1,typename T2>ostream& operator<<(ostream&o,const pair<T1,T2>&v){return o<<v.fi<<","<<v.se;}
template<typename T>bool mins(T& x,const T&y){if(x>y){x=y;return true;}else return false;}
template<typename T>bool maxs(T& x,const T&y){if(x<y){x=y;return true;}else return false;}
template<typename T>ll suma(const v(T)&a){ll res(0);for(auto&&x:a)res+=x;return res;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#define dame { puts("-1"); return;}
#define yn {puts("Yes");}else{puts("No");}
const int MX = 200005;
#define has(x,y) ((x).find(y) != (x).end())

#define int ll
const int mod = 1000000007;

int arr[10];
int h , m;

bool check(int a , int b){
    if(arr[a%10] == -1 || arr[a/10] == -1 || arr[b%10] == -1 || arr[b/10] == -1){
        return 0;
    }
    int x = arr[b%10]*10+arr[b/10];
    int y = arr[a%10]*10+arr[a/10];
    if(x < h && y < m){
        return 1;
    }
    else{
        return 0;
    }
}

struct Solver {
  void solve() {
    // input 
        memset(arr,-1,sizeof(arr));
        arr[0] = 0;
        arr[1] = 1;
        arr[2] = 5;
        arr[5] = 2;
        arr[8] = 8;
      cin >> h >> m;
      string s;
      cin >> s;
      int rh = 0 , rm = 0;
      int n = s.size();
      bool happen = false;
      for(int i = 0 ; i < n ; i++){
        if(s[i] == ':'){
            happen = true;
            continue;
        }
        if(!happen){
            rh = rh*10+s[i]-'0';
        }
        else{
            rm = rm*10+s[i]-'0';
        }
      }
      // cout<<rh<<" "<<rm<?<"\n";
      while(!check(rh,rm)){
        rm++;
        if(rm == m)
            rh++;
        rm%=m;
        rh%=h;
      }
      printf("%02d:",rh);
      printf("%02d\n",rm);
    }
};

int32_t main() {
	ios_base::sync_with_stdio(NULL);
	cin.tie(NULL);
	cout.tie(NULL);
    cout<<fixed<<setprecision(10);
  int ts = 1;
  cin >> ts;
  rrep(ti,ts) {
    Solver solver;
    solver.solve();
  }
  return 0;
}
