HDU4510: Q Series stories-Why cannot I roll back

The Input contains an integer N, indicating that there are N groups of test cases. The next N rows represent N test cases. Each row contains 2 time HH: MM: SS hh: mm: ssHH: MM: SS to indicate the current time, hh: mm: ss indicates the time when you want to go back. [Technical Specification] 00 <= HH <= 1100 <= hh <= 9900 <= MM, SS, mm, ss <= 59 Output: Calculate and Output the time displayed after the clock regresses. The Output format must be HH: MM: SS (two digits are displayed in real time every second. If not, add 0 ), each group of data output occupies one row. Sample Input211: 28: 32 02: 14: 2105: 00: 00 96: 00: 01 Sample Output09: 14: 1104: 59: 59 [cpp] # include <stdio. h> int main () {int h1, m1, r1, h2, m2, r2, h, m, r, n; scanf ("% d", & n ); while (n --) {scanf ("% d: % d", & h1, & m1, & r1, & h2, & m2, & r2); while (r1 <r2) {r1 + = 60; m1 --;} r = r1-r2; while (m1 <m2) {m1 + = 60; h1 --;} m = M1-M2; while (h1