
public class functions {
		static int tong(int a,int b){
			return a+b;
		}
		static int dem(int n){
			int d=0;
			do {
				n=n/10;
				d=d+1;
			}while (n!=0);
			return d;
			
		}
		static void hienthi(int n){
			System.out.println(n);
		}
		static void daonguocso (int n){
			int d;
			do{
			//d=n;
			d=n%10;
			System.out.print(d);
			n=n/10;
			}while(n!=0);
		}
		static void sohoanthien (int n){
			int tong;
			tong=0;
			
			for (int i=1;i<n;i++){
				if(n%i==0){
					tong=tong+i;
				}
			}
			if(tong==n){
				System.out.println(n+" chinh la so hoan thien");
			}else {System.out.println(n+" ko phai so hoan thien");}
				
		}
		static int 
}
