func solve() -> Int {
    guard let G: Int = Int(readLine() ?? ""),
          let P: Int = Int(readLine() ?? "")
    else { return 0 }

    var root: [Int] = Array(0...G)
    
    func find(_ x: Int) -> Int {
        if x != root[x] {
            root[x] = find(root[x])
        }
        return root[x]
    }
    
    func union(_ x: Int, _ y: Int) {
        root[find(y)] = find(x)
    }
    
    var ans: Int = 0
    
    for _ in 0..<P {
        guard let g: Int = Int(readLine() ?? "") else { break }
        
        let target = find(g)
        
        if target == 0 {
            break
        }
        
        ans += 1
        union(target - 1, target)
    }
    
    return ans
}

print(solve())