題意：給你現在的時間，然後問你過了k分鐘後，是幾點了

#include<bits/stdc++.h>
using namespace std;

string s;
int h,m,ss;
int main()
{
    cin>>s;

    for(int i=0;i<2;i++)
        h=h*10+(s[i]-'0');
    for(int i=3;i<s.size();i++)
        m=m*10+(s[i]-'0');
    cin>>ss;
    m +=ss;
    int k = m/60;
    m=m%60;
    h=(h+k)%24;
    printf("%02d:%02d\n",h,m);
}
 

Description 
You are given the current time in 24-hour format hh:mm. Find and print the time after a minutes.

Note that you should find only the time after a minutes, see the examples to clarify the problem statement.

You can read more about 24-hour format here https://en.wikipedia.org/wiki/24-hour_clock.

Input 
The first line contains the current time in the format hh:mm (0 ≤ hh < 24, 0 ≤ mm < 60). The hours and the minutes are given with two digits (the hours or the minutes less than 10 are given with the leading zeroes).

The second line contains integer a (0 ≤ a ≤ 104) — the number of the minutes passed.

Output 
The only line should contain the time after a minutes in the format described in the input. Note that you should print exactly two digits for the hours and the minutes (add leading zeroes to the numbers if needed).

See the examples to check the input/output format.

Sample Input 
Input 
23:59 
10 
Output 
00:09 
Input 
20:20 
121 
Output 
22:21 
Input 
10:10 
0 
Output 
10:10