#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

int exgcd(int a, int b,int &x, int &y) {
    if (b == 0) {
        x = 1;
        y = 0;
        return a;
    }
    int d = exgcd(b, a % b, y, x);
    y -= (a / b) * x;
    return d;
}

string a;
int b,d;
char aa[11111];

int main() {
	scanf("%d%d%s",&b,&d,aa);
	a=aa;
	int ans=0;
	ll pw=1,pd=0;
	for (int i=1;i<=10000;i++) {
		pd=(pd+d*pw)%b;
		pw=pw*10%b;
		int x,y;
		int dd=exgcd(pw,b,x,y);
		if (pd%dd!=0) continue;
		ll Q=b/dd;
		ll P=(x*(-pd/dd))%Q;
		if (P<0) P+=Q;
		if (P==0&&d==0) P+=Q;
		//printf("%d\n",P);
		string sp=to_string(P);
		if (P==0) sp="";
		//P * pw
		//cout<<sp+string(i,d+'0')<<endl;
		int sz=SZ(sp)+i;
		if (sz>SZ(a)) continue;
		if (sz<SZ(a)) ans=max(ans,i);
		else {
			string b=sp+string(i,d+'0');
			if (b<=a) ans=max(ans,i);
		}
		// P * x + Q * y = 1
	}
	printf("%d\n",ans);
}