C :

#include<stdio.h>
int main()
{
    int a,b,c,max;
    scanf("%d%d%d",&a,&b,&c);
    max=a;
    if(b>max)
    max=b;
    if(c>max)
    max=c;
    printf("%d\n",max);
    return 0;
}

C++ :

#include<stdio.h>
int main()
{
  int a,b,c,max;
  scanf("%d%d%d",&a,&b,&c);
  if(a>b)
    max=a;
  else
    max=b;
  if(max>c)
    printf("%d\n",max);
  else
    printf("%d\n",c);
  return 0;
    
}

Pascal :

var a,b,c:longint;
begin
  readln(a,b,c);
  if a>=b then if a>=c then writeln(a);
  if b>a then if b>=c then writeln(b);
  if c>a then if c>b then writeln(c);
end.