#include<stdio.h> int Day(int y, int m, int d) { if ((y % 4 == 0) && (y % 100 != 0) || (y % 400 == 0)) { int c = 0; int x[12] = { 31,29,31,30,31,30,31,31,30,31,30,31 }; for (int i = 0; i < m - 1; i++) { c += x[i]; } ...