#include <iostream> using namespace std; int main() { int n; cin >> n; // 读取输入的月份 // 检查月份是否合法 if (n < 1 || n > 12) { cout << "Invalid." << endl; return 0; } // 根据月份输出天数 switch (n) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: cout << 31 << endl; break; case 4: case 6: case 9: case 11: cout << 30 << endl; break; case 2: cout << 29 << endl; break; } return 0; }