import std.stdio, std.string, std.conv, std.range;
import std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, std.random, core.bitop;

enum inf = 1_001_001_001;
enum infl = 1_001_001_001_001_001_001L;
enum mod = 1_000_000_007L;

void main() {
    int N, K;
    scan(N, K);
    auto a = readln.split.to!(int[]);
    auto am = new int[](N + 1);
    am[0] = 0;
    foreach (i ; 1 .. N + 1) {
        am[i] = max(am[i - 1], a[i - 1]);
    }

    long ans = infl;

    foreach (mask ; 0 .. 1 << N) {
        if (mask.popcnt < K) continue;
        int pre;
        long cost;
        foreach (i ; 0 .. N) if ((mask >> i) & 1) {
            if (max(pre, am[i]) >= a[i]) {
                cost += max(pre, am[i]) - a[i] + 1;
                pre = max(pre, am[i]) + 1;
            }
            else {
                pre = a[i];
            }
        }

        debug {
            writefln("%08b", mask);
            writeln(cost);
        }
        chmin(ans, cost);
    }

    writeln(ans);
}






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;
}
