输入4个整数，找出其中最大的数，用函数嵌套调用来处理

#include<stdio.h>

int main()
{
int max4(int a,int b,int c,int d);
int a;
int b;
int c;
int d;
int max;
printf("Please enter 4 interger number:");
scanf("%d %d %d %d",&a,&d,&c,&d);
max = max4(a,b,c,d);
printf("max = %d\n",max);
return 0;
}

int max4(int a,int b,int c,int d)
{
int max2(int a,int b);
int m;
m = max2(a,b);
m = max2(m,c);
m = max2(m,d);
return m;
}

int max2(int a,int b)
{
if(a >= b)
{
return a;
}
else
{
return b;
}
}