surjective function discrete maths

#include<iostream>
#include<set>
#include<map>
using namespace std;
int f(int x) {
return 4 * x - 7;
}
int g(int x) {
return x * x;
}
bool sureqcia(map <int, int> m, set<int> codom) {
set<int> s;
for (auto im = m.begin(); im != m.end(); im++)
s.insert(im->second); //anasaxebis simravle
for (auto i = codom.begin(); i != codom.end(); i++) {
if (s.find(*i)==s.end()) //codomeinshi edzebs elements, romelic ar aris
anasaxebis simravlesi
{ return false; break; }
}
return true;
}
int main() {
set<int> dom{ -1,-2,1,2};
set<int> codomf{ -11,-15,-3,1};
set<int> codomg{ 1,4,-4 };
map<int, int> mf, mg;
cout << "dom={";
for (auto i = dom.begin(); i != dom.end(); i++) {
cout << *i << ",";
}
cout << "}\n" << endl;
cout << "codomf={";
for (auto i = codomf.begin(); i != codomf.end(); i++) {
cout << *i << ",";
}
cout << "}\n" << endl;
 cout << "codomg={";
for (auto i = codomg.begin(); i != codomg.end(); i++) {
cout << *i << ",";
}
cout << "}\n" << endl;
for (auto i = dom.begin(); i != dom.end(); i++) {
mf[*i] = f(*i); //vqmnit wyvilebis simravles, (i, f(i)), sadac i dom-is
elementia
if (mf.find(*i) == mf.end())
{cout << " asaxva ar aris funqcia\n"; return 0;}
}
cout << "mf: ";
for (auto i = mf.begin(); i != mf.end(); i++)
cout << "(" << i->first << ";" << i->second << "), ";
cout << endl;
if (sureqcia(mf, codomf)) cout << " f sureqciaa \n";
else cout << "f ar aris sureqcia \n";
for (auto i = dom.begin(); i != dom.end(); i++) {
mg[*i] = g(*i); //vqmnit wyvilebis simravles, (i, g(i)), sadac i dom-is
elementia
}
cout << endl;
cout << "mg: ";
for (auto i = mg.begin(); i != mg.end(); i++)
cout << "(" << i->first << ";" << i->second << "), ";
cout << endl;
if (sureqcia(mg, codomg)) cout << "g sureqciaa \n";
else cout << "g ar aris sureqcia \n";
}