Error: expected ')' before ';' token

#include "invoice.h"
#include <iostream>
using namespace std;
 
 
void Invoice::setArt(string a)
{
    art=a;
}
void Invoice::setInfo(string b)
{
    info=b;
}
void Invoice::setX(int y)
{
    x=y;
}
void Invoice::setC(int z)
{
    c=z;
}
string Invoice::getArt()
{
    return art;
}
string Invoice::getInfo()
{
    return info;
}
int Invoice::getX()
{
    return x;
}
int Invoice::getC()
{
    return c;
}
int Invoice::getInvoiceAmount()
{
    return x*c;
}
Invoice::Invoice(string a; string b; int x; int c)
{
    setArt(a);
    setInfo(b);
    if(x<0) x=0;
    setX(x);
    setC(c);
}

#ifndef INVOICE_H_INCLUDED
#define INVOICE_H_INCLUDED
#include <string>
#include <iostream>
using namespace std;
class Invoice
{
public:
    Invoice( int, int);
 
    void setArt(string);
    void setInfo(string);
    void setX (int);
    void setC (int);
 
    string getArt();
    string getInfo();
    int getX();
    int getC();
 
    int getInvoiceAmount();
private:
    string art, info;
    int x, c;
};
 
#endif

#include "invoice.h"
#include <iostream>
using namespace std;
 
int main()
{
    Invoice in1(a; a; 1; 2);
}

Invoice::Invoice(string a; string b; int x; int c)

Invoice::Invoice(string a, string b, int x, int c)
//.......
Invoice in1(a, a, 1, 2);

Invoice( int, int);

Invoice(string a, string b, int x, int c);