#include<stdio.h>

#include<string.h>

#include<math.h>

#include<algorithm>

using namespace std;

int main()

{

    int ansx, ansy;

    int mm, ss, i, j;

    while (~scanf("%d:%d", &mm, &ss))

    {

        if (mm ==  && ss == ) break;

        int t = mm *  + ss;

        int xx, yy;

        int maxn = -;

        int minn = ;

        for (i = ; i <= ; i++)

        {

            for (j = ; j <= ; j++)

            {

                int t9 = i *  + j;

                if ( * abs(t - t9) < t)

                {

                    int sum = ;

                    xx = i, yy = j;

                    if (xx /  == )sum++;

                    if (xx %  == )sum++;

                    if (yy /  == )sum++;

                    if (yy %  == )sum++;

                    if (sum>maxn || (abs(t9 - t) < minn&&sum == maxn))

                    {

                        ansx = xx; ansy = yy;

                        maxn = sum;

                        minn = abs(t9 - t);

                    }

                    sum = ;

                    if (yy <  && xx>)

                    {

                        xx--;

                        yy = yy + ;

                        if (xx /  == )sum++;

                        if (xx %  == )sum++;

                        if (yy /  == )sum++;

                        if (yy %  == )sum++;

                        if (sum > maxn || (abs(t9 - t) < minn&&sum == maxn))

                        {

                            ansx = xx; ansy = yy;

                            maxn = sum;

                            minn = abs(t9 - t);

                        }

                    }

                }

            }

        }

        printf("%02d:%02d\n", ansx, ansy);

    }

    return ;

}