let arr=readLine()!.split{$0==" "}.map{Int(String($0))!}
var n=arr[0]
var k=arr[1]
let arr2=readLine()!.split{$0==" "}.map{Int(String($0))!}
for i in 1...k {
   let j=readLine()!.split{$0==" "}.map{Int(String($0))!}
}

print(n/2)