Finding inverse

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

typedef long long ll;

ll extended_gcd_func(ll a, ll b, ll &x, ll &y) {
    if (b == 0) {
        x = 1;
        y = 0;
        return a;
    }
    ll x1, y1;
    ll d = extended_gcd_func(b, a % b, x1, y1);
    x = y1;
    y = x1 - (a / b) * y1;
    return d;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    ll a, M;
    cin >> a >> M;

    if(M <=1 ){
        cout << "-1";
        return 0;
    }

    ll x, y;
    ll gcd_val = extended_gcd_func(a, M, x, y);

    if(gcd_val !=1 ){
        cout << "-1";
    }
    else{
        ll inverse = x % M;
        if(inverse <=0 ){
            inverse += M;
        }
        cout << inverse;
    }
}

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