public class Solution {
public int solve(ArrayList A) {
Collections.sort(A);
int last= A.size()-1;
for(int i=0;i<A.size();i++){
int j=i;
if(j<last && A.get(j) == A.get(j+1)){
while(j<last && A.get(j) == A.get(j+1)){
j++;
}
i=j;
if((last-j) == A.get(j))return 1;
}else{
if(A.get(i) == (last-i)){
return 1;
}
}
}
return -1;
}
}