#define _USE_MATH_DEFINES #include //cin, cout #include //vector #include //sort,min,max,count #include //string,getline, to_string #include //abs(int) #include //swap, pair #include //deque #include //INT_MAX #include //bitset #include //sqrt, ceil. M_PI, pow, sin #include //fixed #include //setprecision #include //stringstream #include //gcd, assumlate #include //randam_device #include //numeric_limits using namespace std; constexpr int64_t D_MOD = 1000000007; int main() { string N; cin >> N; if (N.at(0) != '1') { cout << -1 << endl; return 0; } for (unsigned int i = 1; i < N.size(); i++) { if (N.at(i) != '3') { cout << -1 << endl; return 0; } } cout << N.size() - 1 << endl; return 0; }