Cf387A

<span style="color:#6600cc;">/*
C - George and Sleep
Time Limit:1000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u
Submit
 
Status
 
Practice
 
CodeForces 387A
Description
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).

Input
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.

Output
In the single line print time p — the time George went to bed in the format similar to the format of the time in the input.

Sample Input
Input
05:50
05:44
Output
00:06
Input
00:00
01:00
Output
23:00
Input
00:01
00:00
Output
00:01
Hint
In the first sample George went to bed at "00:06". Note that you should print the time only in the format "00:06". That's why answers "0:06", "00:6" and others will be considered incorrect.

In the second sample, George went to bed yesterday.

In the third sample, George didn't do to bed at all.
By Grant Yuan
2014.7.11
*/
#include<iostream>
#include<stdio.h>

#include<stdlib.h>
#include<string.h>
using namespace std;
int h1,m1;
int h2,m2;
int main()
{
    scanf("%d:%d",&h1,&m1);
    scanf("%d:%d",&h2,&m2);
    int h3,m3;
    if(m1<m2)
       {h1=(h1+24-1)%24;
         m3=m1+60-m2;
         }
    else m3=m1-m2;
    if(h1<h2)
      h3=(h1+24-h2)%24;
    else h3=h1-h2;
    //cout<<h3<<":"<<m3<<endl;
    if(h3<10)
      cout<<"0"<<h3;
      else
        cout<<h3;
    if(m3<10)
      cout<<":"<<"0"<<m3<<endl;
      else cout<<":"<<m3<<endl;
      return 0;
}
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