B-1026

#include<cstdio>#define CLK_TCK 100int main(){    int c, d;    while(scanf("%d%d", &c, &d)==2){        int ans = d-c;        int a = ans/3600/CLK_TCK; printf("%02d:", a);        int b = (ans-a*3600*CLK_TCK)/60/CLK_TCK; printf("%02d:", b);        int e = ans-3600*a*CLK_TCK-60*b*CLK_TCK;        int tag = 0;        if(e%100 >= 50) tag++;        printf("%02d\n", e/CLK_TCK+tag);    }    return 0;}