George woke up and saw the current time *s* on the digital clock. Besides, George knows that he has slept for time *t*. 

Help George! Write a program that will, given time *s* and *t*, determine the time *p* when George went to bed. Note that George could have gone to bed yesterday relatively to the current time (see the second test sample).
The first line contains current time *s* as a string in the format "hh:mm". The second line contains time *t* in the format "hh:mm" — the duration of George's sleep. It is guaranteed that the input contains the correct time in the 24-hour format, that is, 00 ≤ *hh* ≤ 23, 00 ≤ *mm* ≤ 59.
#include<iostream>
#include<cstring>
using namespace std;
int main()
{
	string a,b;
	int h1=0,h2=0,m1=0,m2=0,a1,a2;
	bool flag=false;
	cin>>a>>b;
	for(int i=0;i<a.size();i++)
		if(flag==false&&a[i]!=':')
			h1*=10,h1+=(a[i]-48);
		else if(a[i]==':')
			flag=true;
		else
			m1*=10,m1+=(a[i]-48);
	flag=false;
	for(int i=0;i<a.size();i++)
		if(flag==false&&b[i]!=':')
			h2*=10,h2+=(b[i]-48);
		else if(b[i]==':')
			flag=true;
		else
			m2*=10,m2+=(b[i]-48);
	if(m1<m2)
		m1+=60,h1--;
	if(h1<h2)
		h1+=24;
	a1=h1-h2;
	a2=m1-m2;
	if(a1<10)
		cout<<0;
	cout<<a1<<':';
	if(a2<10)
		cout<<0;
	cout<<a2;		
	return 0;
}
