用IF THEN 语句帮忙编个输入A,B,C,D 四个数,输出最大值的的算法!

#include
void main()
{
int a, b, c, d;
int max;
printf( "please input a b c d:\n" );
scanf( "%d %d %d %d", &a, &b, &c, &d );
if(a>b)
max =a;
if(c > max)
max=c;
if(d>max)
max=d;
printf( "max is %d", max );
}