Is this a good way to read multiple data from a file using a struct?

Question

I recently started up coding again and there is an exercise which is giving me nightmares.

It's about finding surnames with equal characters. They give me a file which has four values: The first one is an integer that rappresent the number of values that I have to check in the surnames, the second, third and fourth are the surnames, let me give you an example:

2 mazzei marfeo marchica 3 musacchia greca musmeci 4 nicosia nicolosi nicotra

I'm having problems to work with those data, I didn't work a lot with files and structures so I'm struggling a bit, how can I make understand the code that the first value is the number of character that I want to examinate? And more generally, how can I save those information?

This is the code that I made up just for having an idea of how I could do that, don't mind if it's a lot messy.

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <fstream>

using namespace std;

struct Task{
    int caratteriDaConfrontare;
    string cognomi[2];
};

int main(){
    ifstream fin("prova.txt");
    ofstream out;
    out.open("output.txt");
    Task *dati=new Task[255];
    string line;
    int value=dati[0].caratteriDaConfrontare;;
    while(fin>>line){
        for(int i=0; i<value; i++){
            string firstSurname=dati[i].cognomi[0];
            unsigned short surnameLengthI=dati[i].cognomi[0].length();
            string secondSurname=dati[i].cognomi[1];
            unsigned short surnameLengthII=dati[i].cognomi[1].length();
            string thirdSurname=dati[i].cognomi[2];
            unsigned short surnameLengthIII=dati[i].cognomi[2].length();
            for(int x=0; x<surnameLengthI; x++){
                for(int y=0; y<surnameLengthII; y++){
                    for(int z=0; z<surnameLengthIII; z++){
                        if(firstSurname[x]==secondSurname[y])out<<value<<firstSurname<<secondSurname;
                        else if(firstSurname[x]==thirdSurname[z])out<<value<<firstSurname<<thirdSurname;
                        else if(secondSurname[y]==thirdSurname[z])out<<value<<secondSurname<<thirdSurname;
                    }
                }
            }
        }
    }
    fin.close();
    out.close();
    return 0;
}

Of course it's giving me errors, thanks to everyone that'll respond!