export {};
const input = require("fs").readFileSync(0).toString().trim().split("\n").map(Number);
const [G, P]: number[] = [input[0], input[1]]
const gi: number[] = input.slice(2);

let roots: number[] = Array.from({length : G+1}, (_, i) => i);

const find = (g: number): number => {
    if(roots[g] !== g) roots[g] = find(roots[g]);
    return roots[g];
}

const union = (a: number, b: number) => {
    roots[find(a)] = find(b);
}

let ans: number = 0;

for(let i=0; i<P; i++) {
    const p = find(gi[i]);

    if(p === 0) break;

    union(p, p-1);
    ans++;
}

console.log(ans);