#include <iostream>
#include <algorithm>
using namespace std;
int main() {
string s;
string t;
cin >> s >> t;
int b = 0;
int sum = 1;
for (int i = 0; i < t.size(); i++) {
if (s[b] == t[i]) {
sum++;
b++;
}
}
cout << sum << endl;
}
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