Работа со Структурами

#include "stdafx.h"
#include "iostream.h"
#include "string.h"
#include "stdlib.h"
#include "windows.h"
#include "time.h"

struct stud
{char surname[25];
int exam[5];
float stredb;
};

void main()
{stud i31[20];
    for(int n = 0; n < 20; n++)
    {cout<<"Vvedite familiy: \n";
        cin>>i31.surname;
        for(int m = 0; m < 5; m++)
            i31[n].exam[m];
    }

for(int m = 0; m < 5; m++)
{   buft = i31[n].exam[m];
    i31[n].sredb = buft;
    cout<<"\n familia: "<<"Stred bal: "<<i31[n].sredb;
    cout<<endl;
}
}

--------------------Configuration: struct - Win32 Debug--------------------
Compiling...
struct.cpp
E:\C++ my project\structuri\struct\struct.cpp(21) : error C2228: left of '.surname' must have class/struct/union type
E:\C++ my project\structuri\struct\struct.cpp(27) : error C2065: 'buft' : undeclared identifier
E:\C++ my project\structuri\struct\struct.cpp(28) : error C2039: 'sredb' : is not a member of 'stud'
        E:\C++ my project\structuri\struct\struct.cpp(12) : see declaration of 'stud'
E:\C++ my project\structuri\struct\struct.cpp(29) : error C2039: 'sredb' : is not a member of 'stud'
        E:\C++ my project\structuri\struct\struct.cpp(12) : see declaration of 'stud'
Error executing cl.exe.

struct.exe - 4 error(s), 0 warning(s)