#include<stdio.h>

int main(void)  
{  
    int late, hh, mm;  
    float s, v, t;  
    float school = 480.0;   
    scanf("%f%f", &s, &v);  
    t = s / v;  
    late = (int)(school - (10+t));  
    if (late < 0)  
        late += 24 * 60;  
    hh = late / 60;  
    mm = late % 60;  
    if (hh < 10)  
    {  
        if (mm < 10)  
            printf("0%d:0%d", hh, mm);  
        else  
            printf("0%d:%d", hh, mm);  
    }  
    else  
    {  
        if (mm < 10)  
            printf("%d:0%d", hh, mm);  
        else  
            printf("%d:%d", hh, mm);  
    }  

    return 0;  
}