Finding inverse

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;

tuple<ll,ll,ll> gcd(ll a, ll b){
    if(!b)
        return {a,1,0};
    const auto&[gcd2,x,y] = gcd(b,a%b);
    return {gcd2, y, x-(a/b)*y};
}

ll modinv(ll a, ll m){
    const auto&[d,e,f]=gcd(a,m);
    if(d != 1)
        return -1;
    auto inv = (e+m)%m;
    return inv;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    ll a, m;
    cin >> a >> m;

    if(!a || !m){
        cout << -1 << "\n";
        return 0;
    }

    ll inv = modinv(a, m);
    cout << ((inv <= 0 || inv > m) ? (inv == m ? -1 : inv) : inv) << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED