var n = parseInt(read_line()), line, list = [0];
for(var k = 1; k < n; k++){
      var arr = read_line().split(' ');
      list[parseInt(arr[1])] = parseInt(arr[0]);
}
function find(child, len){
      len++;
      if(!child){
            return len;
      }else{
            return find(list[child], len);
      }
}
var lenList = [];
for(var i = 0; i < n; i++){
      lenList.push(find(list[i], 0));
};
print(Math.max.apply(null, lenList));