// @BEGIN_OF_SOURCE_CODE

/* @JUDGE_ID:  17243NT  161  C++  "Simulate" */

// Send to judge@uva.es

#include <iostream.h>
#include <fstream.h>
#include <iomanip.h>

#ifdef ONLINE_JUDGE
	#define ins cin
	#define outs cout
#else
	#define ins fin
	#define outs fout
	ifstream fin("myprog.in");
	ofstream fout("myprog.out");
#endif

int gt[110];
bool stats[110];
int time[110];
bool init;
int nlights, total;

int sec;

void green(int i);
void ungreen(int i);

int main() {
	int i;
	
	while(ins >> gt[0] >> gt[1] >> gt[2]) {
		if(gt[0] == 0 && gt[1] == 0 && gt[2] == 0) break;
		if(gt[2] == 0) {
			nlights = 2;
		} else {
			nlights = 3;
			for(;;) {
				ins >> gt[nlights];
				if(gt[nlights] == 0) break;
				nlights++;
			}
		}
		init = true;
		total = 0;
		sec = 0;
		for(i = 0; i < nlights; i++)
			green(i);
		
		for(;;) {
			sec++;
			for(i = 0; i < nlights; i++) {
				if(--time[i] <= 0) {
					if(stats[i]) ungreen(i);
					else green(i);
				}
			}
			
			if(sec > 18000) {
				outs << "Signals fail to synchronise in 5 hours\n";
				break;
			} else if(!init && total == nlights) {
				int hr = sec / 3600;
				int min = (sec / 60) % 60;
				
				sec = sec % 60;
				
				if(hr == 0) outs << "00";
				else if(hr < 10) outs << "0" << hr;
				else outs << hr;
				outs << ":";

				if(min == 0) outs << "00";
				else if(min < 10) outs << "0" << min;
				else outs << min;
				outs << ":";

				if(sec == 0) outs << "00";
				else if(sec < 10) outs << "0" << sec;
				else outs << sec;
				outs << "\n";

				break;
			}
		}
	}
	
	return 0;
}

void green(int i) {
	total++;
	stats[i] = true;
	time[i] = gt[i] - 5;
}

void ungreen(int i) {
	init = false;
	total--;
	stats[i] = false;
	time[i] = gt[i] + 5;
}

// @END_OF_SOURCE_CODE