3.5

#include<iostream>
using namespace std;
class student{
private:
int num;
int c;
public:
friend int max(student *p);
    student(int n,int m):num(n),c(m){}

}*p;
student s[5]={
student(1,57),
student(2,68),
student(3,78),
student(4,48),
student(5,76),
};


int max(student *p){
int max;
max=0;
for(int i=0;i<5;i++)
if(max<p->c)
{ max=p->c;
   p++;
}
return max;
}
int main(){
    p=s;
cout<<max(p);
return 0;
}