import std.algorithm;
import std.array;
import std.conv;
import std.math;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;

int calc(int[] xs) {
    int n = cast(int)xs.length;
    return max(xs.sum, (xs[0] - 1) + (9 * (n - 1)));
}

void main() {
    auto s = readln.chomp;
    auto xs = s.map!(e => cast(int)(e - '0')).array;

    auto ans = calc(xs);
    writeln(ans);
}
