Problem:
Score : 500 points

Problem Statement

Given are two strings s and t consisting of lowercase English letters. Determine if there exists an integer i satisfying the following condition, and find the minimum such i if it exists.

Let s' be the concatenation of 10^{100} copies of s. t is a subsequence of the string {s'}_1{s'}_2\ldots{s'}_i (the first i characters in s').

Notes

A subsequence of a string a is a string obtained by deleting zero or more characters from a and concatenating the remaining characters without changing the relative order. For example, the subsequences of contest include net, c, and contest.

Constraints

1 \leq |s| \leq 10^5

1 \leq |t| \leq 10^5

s and t consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

s
t

Output

If there exists an integer i satisfying the following condition, print the minimum such i; otherwise, print -1.

Sample Input 1

contest
son

Sample Output 1

10

t = son is a subsequence of the string contestcon (the first 10 characters in s' = contestcontestcontest...), so i = 10 satisfies the condition.

On the other hand, t is not a subsequence of the string contestco (the first 9 characters in s'), so i = 9 does not satisfy the condition.

Similarly, any integer less than 9 does not satisfy the condition, either. Thus, the minimum integer i satisfying the condition is 10.

Sample Input 2

contest
programming

Sample Output 2

-1

t = programming is not a substring of s' = contestcontestcontest.... Thus, there is no integer i satisfying the condition.

Sample Input 3

contest
sentence

Sample Output 3

33

Note that the answer may not fit into a 32-bit integer type, though we cannot put such a case here.

Solution in JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

function Main(input) {
 
    var s = input.split('\n')[0];
    var str = s;
    var t = input.split('\n')[1];

    var set = new Set(t.split(''));

    for (var x of set) {
        if (s.indexOf(x) === -1) {
            console.log(-1);
            return;
        }
    }

    var ans = 0;
    var f = true;
    var first = 0;
    while (1) {
        var tmp = s.length;
        for (var i = 0; i < t.length; i++){
            var a = s.substr(0, tmp).lastIndexOf(t[t.length - 1 - i]);
            if (tmp < a || a === -1) {
                f = false;
                break;
            }
            if (i === 0) first = a;
            tmp = a;
        }
        if (f) {
            ans = tmp;
            break;
        }
        s = s + str;
        f = true;
    }

    console.log(first+1);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));