importjava.util.*;publicclassMain{privatestaticfinalString[]range =newString[5];privatestaticint[] sum =newint[10];privatestaticvoidinit(){
range[0]="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
range[1]="abcdefghijklmnopqrstuvwxyz";
range[2]="0123456789";
range[3]="~!@#$%^&*()_+/-=[]{};:'<>?.";}privatestaticintnextInt(int len){Random random =newRandom();returnMath.abs(random.nextInt(len));}privatestaticchargetChar(int op){return range[op].charAt(nextInt(range[op].length()));}privatestaticchargetRand(){int op =nextInt(4);returngetChar(op);}publicstaticvoidmain(String[] args){init();StringBuffer s =newStringBuffer();Arrays.fill(sum,0);for(int i =0; i <16; i++){
s.append(getRand());}for(int i =0; i <4; i++){if(sum[i]==0){
s.append(getChar(i));}}System.out.println(s);}}