diff --git a/S2OJ/857/857.cpp b/S2OJ/857/857.cpp
new file mode 100644
index 00000000..95187e89
--- /dev/null
+++ b/S2OJ/857/857.cpp
@@ -0,0 +1,17 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, a, l, r;
+string s, s1, s2;
+
+int main() {
+    getline(cin, s, ',');
+    getline(cin, s1, ',');
+    getline(cin, s2);
+    n = s.find(s1);
+    a = s.rfind(s2);
+    l = s1.size();
+    r = s2.size();
+    cout << (a <= n || a == -1 || n == -1 || a < n + l - 1 ? -1 : a - n - l) << endl;
+}