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class Solution{
static String largestNumber(int n, int sum) {
if(n*9<sum){
return "-1";
}
StringBuffer sb=new StringBuffer();
for(int i=0;i<n;i++){
int t;
if(sum>9){
sum-=9;
t=9;
}
else if(sum==0){
t=0;
}
else{
t=sum;
sum-=t;
}
sb.append(t);
}
return sb.toString();
}
}