#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
using namespace std;
long long MOD = 998244353;
double eps = 1e-12;
void solve() {}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  string a, b;
  cin >> a >> b;
  int i = 0;
  for (int j = 0; j < b.size(); ++j) {
    if (b[j] == a[i]) {
      i++;
    }
  }
  cout << i + 1 << endl;
}
