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));