#include<stdio.h>
int main() {
    int s,v,h,m,hh,mm;
    scanf("%d%d",&s,&v);
    int t=s/v+10;
    if(s%v!=0){
    	t++;
	}
	if(t>=60){
		h=t/60;
		m=t%60;
	}else if(t<60){
		h=0;
		m=t;
	}
	if(m<60&&m!=0){
	  if(7-h>0){
		hh=7-h;
	    mm=60-m;	
	  }else if(7-h<0){
		hh=24+7-h;
		mm=60-m;
	  }
	}else if(m==0){
		if(8-h>0){
		hh=8-h;
	    mm=0;	
	 }else if(8-h<=0){
		hh=24+8-h;
		mm=0;
	 }
	}
	if(hh<=8&&hh>0&&mm>=10){
		printf("0%d:%d",hh,mm);
		
	}else if(hh<=8&&hh>0&&mm<10){
		
		printf("0%d:0%d",hh,mm);
		
	}else if(hh<24&&hh>8&&mm>=10){
		
		printf("%d:%d",hh,mm);
		
	}else if(hh<24&&hh>8&&mm<10){
		
		printf("%d:0%d",hh,mm);
		
	}else if(h==8){
		if(mm>=10){
			
			printf("23:%d",mm);
			
		}else if(mm<10&&mm>0){
			
			printf("23:0%d",mm);
			
		}if(mm==0){
			
			printf("00:00");
		}
		
	}
    return 0;
}
```cpp