#include<stdio.h>
int max_2(int a,int b)
{
return a>b?a:b;
}
int max_4(int a,int b,int c,int d)
{
int m;
m = max_2(a,b);
m = max_2(m,c);
m = max_2(m,d);
return m;
}
int main()
{
int a,b,c,d;
printf("please input 4 number:\n");
scanf("%d%d%d%d",&a,&b,&c,&d);
printf("max=%d\n",max_4(a,b,c,d));
return 0;
}