import java.util.*;
import java.lang.*;
import java.io.*;
class Main {
Scanner read
= new Scanner
(System.
in); int sh = read.nextInt();
//char sym = read.nextChar();
int sm = read.nextInt();
int fh = read.nextInt();
int fm = read.nextInt();
int way = read.nextInt();
int rest = read.nextInt();
int start = sh*60 + sm;
int finish = fh*60 + fm;
int x = way + rest;
for(int t = start, i = 0; t < finish; t += x, i++){
System.
out.
print(t
/60+":"+t
%60
); if(i%2 == 0)
else
}
}
}
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