题解 | #合法IP#

let input;
while (input = readline()) {
    let arr = input.split('.');
    let result = 'YES';
    for (let i = 0; i < arr.length; i++) {
        if (parseInt(arr[i]) < 0 || parseInt(arr[i]) > 255) {
            result = 'NO';
            break;
        }
    }
    
    print(result);
}