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() {
    char[] s;
    scan(s);

    int ans = 100000;

    foreach (ch ; 'a' .. 'z' + 1) {
        ans = min(ans, solve(s, ch.to!char));
    }

    writeln(ans);
}

int solve(char[] s, char ch) {
    int n = s.length.to!int;
    char[] cur = s.dup;

    foreach (i ; 0 .. n - 1) {
        bool ok = true;

        foreach (j ; 0 .. cur.length) {
            if (cur[j] != cur[0]) {
                ok = false;
                break;
            }
        }

        if (ok) {
            return i;
        }

        auto nex = new char[](n - 1 - i);
        foreach (j ; 0 .. n - 1 - i) {
            if (cur[j] == ch || cur[j + 1] == ch) {
                nex[j] = ch;
            }
            else {
                nex[j] = cur[j];
            }
        }
        cur = nex;

        debug {
            writeln(cur);
        }
    }

    return 1000000;
}





















int[][] readGraph(int n, int m, bool isUndirected = true, bool is1indexed = true) {
    auto adj = new int[][](n, 0);

    foreach (i; 0 .. m) {
        int u, v;
        scan(u, v);
        if (is1indexed) {
            u--, v--;
        }
        adj[u] ~= v;
        if (isUndirected) {
            adj[v] ~= u;
        }
    }

    return adj;
}

alias Edge = Tuple!(int, "to", int, "cost");

Edge[][] readWeightedGraph(int n, int m, bool isUndirected = true, bool is1indexed = true) {
    auto adj = new Edge[][](n, 0);

    foreach (i; 0 .. m) {
        int u, v, c;
        scan(u, v, c);
        if (is1indexed) {
            u--, v--;
        }
        adj[u] ~= Edge(v, c);
        if (isUndirected) {
            adj[v] ~= Edge(u, c);
        }
    }

    return adj;
}

void yes(bool b) {
    writeln(b ? "Yes" : "No");
}

void YES(bool b) {
    writeln(b ? "YES" : "NO");
}

T[] readArr(T)() {
    return readln.split.to!(T[]);
}

T[] readArrByLines(T)(int n) {
    return iota(n).map!(i => readln.chomp.to!T).array;
}

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);
        }
    }
}

bool chmin(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x > arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}

bool chmax(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x < arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}
