#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN=2200000,Mod=2181271;
int Hash[MAXN];
struct P{
    ll val;
    int next;
}p[MAXN];
bool Count(int pos,ll x){
    for(int i=Hash[pos]; i ;i = p[i].next)
        if(p[i].val == x)
            return 1;
    return 0;
}
int A,B,C;
int main(){
    ll a = 1;
    Hash[1] = p[1].val = 1;
    scanf("%d%d%d",&A,&B,&C);
    for(int i=1;i<=2000000;i++){
        a=(a*A+a%B)%C;
        int pos=a%Mod;
        if(Count(pos,a)){
            printf("%d\n",i);
            return 0;
        }
        p[i+1]={a,Hash[pos]};
        Hash[pos]=i+1;
    }
    printf("-1\n");
    return 0;
}