C :

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

C++ :

#include <iostream>
using namespace std;

int max(int x,int y)
  {
    if(x<y)
      return y;
    else
      return x;
  }
int main()
{
  int a,b,c,z;
  cin>>a>>b>>c;
  z=max(max(a,b),c);
    cout<<z<<endl;
return 0;	  
}

Pascal :

program t21243;
var a,b,c,max:integer;
begin
 readln(a,b,c);
 max:=a;
 if max<b then max:=b;
 if max<c then max:=c;
 writeln(max);
end.