C :

# include<stdio.h>
int main()
  {
  int a,b,c,d;
  a=2;
  b=-3;
  c=9;
  d=max(a,b,c);
  printf("max=%d\n",d);
  return 0;
  }
int max(int x,int y,int z)
  {
  int w,s;
  if(x>y)w=x;
  else w=y;
  if(w>z)s=w;
  else s=z;
  return(s);
  }
  

C++ :

#include <stdio.h>
int main(int argc, char *argv[])
{
	int a,b,c;
	scanf("%d%d%d",&a,&b,&c);
	printf("max=%d\n",(a>b?a:b)>c?(a>b?a:b):c);
	return 0;
}