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

template <typename A, typename B>
string to_string(pair<A, B> p);
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
 
string to_string(const string& s) {
  return '"' + s + '"';
}
 
string to_string(const char* s) {
  return to_string((string) s);
}
 
string to_string(bool b) {
  return (b ? "true" : "false");
}
 
string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}
 
template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}
 
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
 
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
 
void debug_out() { cerr << endl; }
 
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

#define fi first
#define se second
#define pb push_back
#define mod(n,k) ( ( ((n) % (k)) + (k) ) % (k))
#define forn(i,a,b) for(int i = a; i < b; i++)
#define forr(i,a,b) for(int i = a; i >= b; i--)
#define all(x) (x).begin(), (x).end()

typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;

const ll mod = 1e9+7;
ll mul(ll a,ll b){return ((a%mod)*(b%mod))%mod;}
ll sum(ll a,ll b){return ((a%mod)+(b%mod))%mod;}
ll sub(ll a,ll b){return ((a%mod)-(b%mod))%mod;}
ll power(ll a,ll b){
	ll res = 1;
	while(b){
		if(b&1)res = mul(res,a);
		b >>= 1;
		a = mul(a,a);
	}
	return res;
}

const int maxn = 1000+10;
ll fib[maxn];

int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	fib[2] = fib[3] = 1;
	forn(i,4,maxn)fib[i] = sum(fib[i-1],fib[i-2]);
	int N; cin >> N;
	char aa,ab,ba,bb; cin >> aa >> ab >> ba >> bb;
	if(N <= 3){
		cout << 1 << '\n';
		return 0;
	}
	ll res = 0;
	if(ab == 'A'){
		if(aa == 'A'){
			res = 1;
		}else{
			if(ba == 'B'){
				res = power(2,N-3);
			}else{
				res = fib[N];
			}
		}
	}else{
		if(bb == 'B'){
			res = 1;
		}else{
			if(ba == 'A'){
				res = power(2,N-3);
			}else{
				res = fib[N];
			}
		}
	}
	if(res < 0)res += mod;
	cout << res << '\n';
	return 0;
}
/*
__builtin_mul_overflow(x,y,&x)
-fsplit-stack
*/

#include <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define FOR(i, n, m) for(int i = (int)(n); i < (int)(m); i++)
using namespace std;
 
int main() {
  int N, X;
  cin >> N >> X;
  vector<vector<int>> Alc(N, vector<int>(2));
  rep(i, N) cin >> Alc[i][0] >> Alc[i][1];
  
  bool flag = false;
  int ml = 0;
  int ans;
  rep(i, N) {
    ml += Alc[i][0]*Alc[i][1];
    cerr << i+1 << " " << ml << endl;
    if (ml > X*100) {
      ans = i+1;
      flag = true;
      break;
    }
  }
  if (flag) {
    cout << ans << endl;
  } else {
    cout << -1 << endl;
  }
}