import std.stdio, std.string, std.conv; import std.range, std.algorithm, std.array, std.typecons, std.container; import std.math, std.numeric, core.bitop; enum inf3 = 1_001_001_001; enum inf6 = 1_001_001_001_001_001_001L; enum mod = 1_000_000_007L; void main() { string n; scan(n); if (!n[1 .. $].all!"a == '3'") { writeln(-1); } else { writeln(n.count!"a == '3'"); } } struct ModComb { int _N; long[] _fact, _factinv; long _mod; this(int n, long mod = 1_000_000_007L) { _N = n; _fact = new long[](_N + 1); _factinv = new long[](_N + 1); _mod = mod; _fact[0] = 1; foreach (i ; 1 .. _N + 1) { _fact[i] = (_fact[i-1] * i) % mod; } _factinv[_N] = _powmod(_fact[_N], mod - 2); foreach_reverse (i ; 0 .. _N) { _factinv[i] = (_factinv[i+1] * (i+1)) % mod; } } long c(int n, int k) { return f(n) * finv(n - k) % _mod * finv(k) % _mod; } long p(int n, int r) { return f(n) * finv(n - r) % _mod; } long f(int n) { return _fact[n]; } long finv(int n) { return _factinv[n]; } long _powmod(long x, long y) { return y > 0 ? _powmod(x, y>>1)^^2 % _mod * x^^(y & 1) % _mod : 1; } } void yes(bool b) {writeln(b ? "Yes" : "No");} void YES(bool b) {writeln(b ? "YES" : "NO");} T[] readArr(T)() {return readln.split.to!(T[]);} void scan(T...)(ref T args) { import std.stdio : readln; import std.algorithm : splitter; import std.conv : to; import std.range.primitives; auto line = readln().splitter(); foreach (ref arg; args) { arg = line.front.to!(typeof(arg)); line.popFront(); } assert(line.empty); } void fillAll(R, T)(ref R arr, T value) { static if (is(typeof(arr[] = value))) { arr[] = value; } else { foreach (ref e; arr) { fillAll(e, value); } } }