import copy
if __name__ == "__main__":
s, t = str(input()), str(input())
n = len(s)
pos = [0] * 26
for i in range(26):
pos[i] = n
nxt = [[0] * 26] * n
for k in range(2):
for i in range(n-1, -1, -1):
nxt[i] = copy.deepcopy(pos)
pos[ord(s[i]) - ord("a")] = i
ans, i = 1, 0
for j in range(1 if s[0] == t[0] else 0, len(t), 1):
next = nxt[i][ord(t[j]) - ord("a")]
if next == n:
print(-1)
exit()
if next <= i:
ans += 1
i = next
print(ans)#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> p32;
typedef pair<ll, ll> p64;
typedef pair<double, double> pdd;
typedef vector<ll> v64;
typedef vector<int> v32;
typedef vector<vector<int> > vv32;
typedef vector<vector<ll> > vv64;
typedef vector<vector<p64> > vvp64;
typedef vector<p64> vp64;
typedef vector<p32> vp32;
ll MOD = 1000000007;
double eps = 1e-12;
#define ln "\n"
#define printVector(a) for(int i=0; i<a.size(); i++){cout<<a[i]<<" ";}cout<<ln;
#define print_array(a,n) for(int i=0; i<n; i++){cout<<a[i]<<" ";}cout<<ln;
#define dbg(x) cout<<#x<<" = "<<x<<ln
#define mp make_pair
#define pb push_back
#define take_vector(a) for(auto &x:a)cin>>x;
#define take_array(a,n) for(int i=0;i<n;i++){cin>>a[i];}
#define take_matrix(a,m,n) for(int i=0; i<m; i++){for(int j=0; j<n; j++){cin>>a[i][j];}}
#define print_matrix(a,m,n) for(int i=0; i<m; i++){for(int j=0; j<n; j++){cout<<a[i][j]<<" ";}cout<<ln;}
#define fi first
#define se second
#define INF 2e18
#define fast_cin() ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) (a/gcd(a,b))*b
#define count(a,x) count(a.begin(), a.end(),x)
#define sum(a) accumulate(a.begin(), a.end(),0)
#define max_ele(a) *max_element(a.begin(), a.end())
#define min_ele(a) *min_element(a.begin(), a.end())
void solve() {
string s, t;
cin >> s >> t;
int n = s.size();
int m = t.size();
set<int> pos[26];
for(int i = 0; i<n; i++) {
pos[s[i]-'a'].insert(i);
}
int ans = 1, lastIndex = -1;
for(int i= 0; i<m; i++) {
int ch = t[i]-'a';
if(pos[ch].size() == 0) {
cout << -1 << ln;
return;
}
auto it = pos[ch].upper_bound(lastIndex);
if(it == pos[ch].end()) {
ans++;
lastIndex = *pos[ch].begin();
}
else{
lastIndex = *it;
}
}
cout << ans << ln;
}
int main()
{
#ifndef ONLINE_JUDGE
// freopen("input.txt","r",stdin);
// freopen("output.txt","w",stdout);
#endif
fast_cin();
ll t = 1;
// cin >> t;
// for (int it = 1; it <= t; it++)
// {
// //cout << "Case #" << it+1 << ": ";
// solve();
// }
solve();
return 0;
}589. N-ary Tree Preorder Traversal | 1299. Replace Elements with Greatest Element on Right Side |
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