#include <iostream>
using namespace std;

// 快速幂取模函数，计算 (base^exponent) % mod
int fastPower(int base, int exponent, int mod) {
    int result = 1;
    base %= mod;
    while (exponent > 0) {
        if (exponent & 1) {
            result = (result * base) % mod;
        }
        base = (base * base) % mod;
        exponent >>= 1;
    }
    return result;
}

int main() {
    int p, b, n;
    cin >> p >> b >> n;
    for (int l = 0; l < p; l++) {
        if (fastPower(b, l, p) == n) {
            cout << l << endl;
            return 0;
        }
    }
    cout << -1 << endl;
    return 0;
}