import java.util.Scanner
import java.lang.String.format

fun main() {
    val sc = Scanner(System.`in`)
    var s = sc.nextLine().split(':')
    val ch = Integer.parseInt(s[0])
    val cm = Integer.parseInt(s[1])
    val cs = Integer.parseInt(s[2])
    s = sc.nextLine().split(':')
    var sh = Integer.parseInt(s[0]) + 24
    var sm = Integer.parseInt(s[1])
    var ss = Integer.parseInt(s[2])
    var rh: Int
    var rm: Int
    var rs: Int
    if (cs > ss) {
        sm--
        ss += 60
    }
    rs = ss - cs
    if (cm > sm) {
        sh--
        sm += 60
    }
    rm = sm - cm
    rh = sh - ch
    if (rh >= 24) rh -= 24
    print(format("%02d:%02d:%02d", rh, rm, rs))
}