Fix

src/main.cpp

@@ -64,7 +64,7 @@ void parseArgument(const string& arg, int &dayNum, bool &useTestInput, int &test
 	}
 	dayNum = stoi(arg.substr(0, tIndex));
 	useTestInput = true;
-	testFetchIndex = stoi(arg.substr(tIndex + 1));
+	testFetchIndex = tIndex + 1 < arg.size() ? stoi(arg.substr(tIndex + 1)) : 0;
 }
 
 int main(int argc, char *argv[]) {