Getter and Setter Functions for a class within a class

I'm not sure if I am being incredibly stupid but what are your opinions on how I should set values in a class by using getter and setter functions.

Should I either do :

Class A
{
private:

int a;
int b;
int c;

public:

void setClass(int a,int b,int c);
}

or should I do this :

Class A
{
private:

int a;
int b;
int c;

public:

void setA(int a);
void setB(int B)/>;
void setC(int c);

}

Any help would be appreciated.