Baekjoon #3029

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) throws IOException{
        FastReader rd = new FastReader();
        System.out.print(solve(rd.nextLine(), rd.nextLine()));
    }

    public static String solve(String s1, String s2) {
        if(s1.equals(s2)) {
            return "24:00:00";
        }

        int h = Integer.parseInt(s2.split(":")[0]) - Integer.parseInt(s1.split(":")[0]);
        int m = Integer.parseInt(s2.split(":")[1]) - Integer.parseInt(s1.split(":")[1]);
        int s = Integer.parseInt(s2.split(":")[2]) - Integer.parseInt(s1.split(":")[2]);

        if(s < 0) {
            s += 60;
            m--;
        }

        if(m < 0) {
            m += 60;
            h--;
        }

        if(h < 0) {
            h += 24;
        }

        return String.format("%02d:%02d:%02d", h, m, s);
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while(st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() { return Integer.parseInt(next()); }
        long nextLong() { return Long.parseLong(next()); }
        double nextDouble() { return Double.parseDouble(next()); }
        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}

import sys
def input():
    return sys.stdin.readline().rstrip()

def isBig():
    if start[0] < end[0]:
        return 1
    elif start[0] == end[0]:
        if start[1] < end[1]:
            return 1
        elif start[1] == end[1]:
            if start[2] < end[2]:
                return 1
            elif start[2] == end[2]:
                return 0
            else:
                return -1
        else:
            return -1
    else:
        return -1
            
start = list(map(int, input().split(':')))
end = list(map(int, input().split(':')))
total = start[0] * 3600 + start[1] * 60 + start[2]
total2 = end[0] * 3600 + end[1] * 60 + end[2]
if isBig() == 1:
    ans = total2 - total
    hour, minute, second = str(ans // 3600), str(ans % 3600 // 60), str(ans % 60)
    hour = '0' * (2-len(hour)) + hour
    minute = '0' * (2-len(minute)) + minute
    second = '0' * (2-len(second)) + second
    print(f"%s:%s:%s" % (hour, minute, second))
elif isBig() == 0:
    print('24:00:00')
else:
    ans = total2 - total + 3600 * 24
    hour, minute, second = str(ans // 3600), str(ans % 3600 // 60), str(ans % 60)
    hour = '0' * (2-len(hour)) + hour
    minute = '0' * (2-len(minute)) + minute
    second = '0' * (2-len(second)) + second
    print(f"%s:%s:%s" % (hour, minute, second))