function sumAge(user) {}
 
const user1 = {
  name: "Петр",
  age: 49,
  children: [
    {
      name: "Ника",
      age: 25,
      children: [
        {
          name: "Андрей",
          age: 3,
        },
        {
          name: "Олег",
          age: 1,
        },
      ],
    },
    {
      name: "Александр",
      age: 22,
    },
  ],
};
 
console.log(sumAge(user1)); // 100

function sumAge(user) {
  let resAge = user.age;
 
  if (user.children) {
    for (let i = 0; i < user.children.length; i++) {
      resAge = resAge + sumAge(user.children[i]);
    }
  }
 
  return resAge;
}