#include
#include<string.h>
#include
#include
using namespace std;
int main()
{
int ansx, ansy;
int mm, ss, i, j;
while (~scanf("%d:%d", &mm, &ss))
{
if (mm == 0 && ss == 0) break;
int t = mm * 60 + ss;
int xx, yy;
int maxn = -1;
int minn = 999999999;
for (i = 0; i <= 99; i++)
{
for (j = 0; j <= 99; j++)
{
int t9 = i * 60 + j;
if (10 * abs(t - t9) < t)
{
int sum = 0;
xx = i, yy = j;
if (xx / 10 == 9)sum++;
if (xx % 10 == 9)sum++;
if (yy / 10 == 9)sum++;
if (yy % 10 == 9)sum++;
if (sum>maxn || (abs(t9 - t) maxn))
{
ansx = xx; ansy = yy;
maxn = sum;
minn = abs(t9 - t);
}
sum = 0;
if (yy <40 && xx>0)
{
xx--;
yy = yy + 60;
if (xx / 10 == 9)sum++;
if (xx % 10 == 9)sum++;
if (yy / 10 == 9)sum++;
if (yy % 10 == 9)sum++;
if (sum > maxn || (abs(t9 - t) maxn))
{
ansx = xx; ansy = yy;
maxn = sum;
minn = abs(t9 - t);
}
}
}
}
}
printf("%02d:%02d\n", ansx, ansy);
}
return 0;
}