C :

#include <stdio.h>
void main()
{
	int x,y,a,b,c;
	scanf("%d",&x);
	a=x/100;
	b=x/10%10;
	c=x%10;
	if(a>b)
		if(b>c)
			y=x;
		else
			if(a>c)
				y=a*100+c*10+b;
			else
				y=c*100+a*10+b;
	else
		if(a>c)
			y=b*100+a*10+c;
		else
			if(b>c)
				y=b*100+c*10+a;
			else
				y=c*100+b*10+a;
	printf("%d\n",y);
}

C++ :

#include<bits/stdc++.h>
using namespace std;
int n,a[5];
int main()
{   
    cin>>n;
    a[1]=n/100;a[2]=n%100/10;a[3]=n%10;
    sort(a+1,a+4);
    printf("%d%d%d",a[3],a[2],a[1]);
    return 0; 
}

Pascal :

var x,g,s,b,y,t:integer;
begin
	readln(x);
	g:=x mod 10;
	b:=x div 100;
	s:=x div 10 mod 10;
	if b<s then begin t:=b;b:=s;s:=t;end;
	if b<g then begin t:=b;b:=g;g:=t;end;
	if s<g then begin t:=s;s:=g;g:=t;end;
	y:=b*100+s*10+g;
	writeln(y);
end.