/* */ #include <iostream> #include <string> #include <algorithm> #include <functional> #include <vector> #include <stack> #include <queue> #include <set> #include <bitset> #include <map> #include <cstdio> #include <cstdlib> #include <cstring> #include <cmath> using namespace std; typedef long long ll; typedef pair<int,int> pint; typedef vector<int> vint; typedef vector<pint> vpint; #define mp make_pair #define fi first #define se second #define all(v) (v).begin(),(v).end() #define rep(i,n) for(int i=0;i<(n);i++) #define reps(i,f,n) for(int i=(f);i<(n);i++) int dx[4] = {1, 0, 0, -1}; int dy[4] = {0, 1, -1, 0}; int main(void){ int n, m; scanf("%d %d", &n, &m); int tmp_sei[m]; int tmp_fu[m]; int sei = 0, zero = 0, fu = 0, tmp; rep(i, m){ scanf("%d", &tmp); if (tmp > 0){ tmp_sei[sei] = tmp; sei++; }else if(tmp == 0){ zero++; }else{ tmp_fu[fu] = tmp; fu++; } } vector<int> d_sei(sei); vector<int> d_fu(fu); rep(i, sei) d_sei[i] = tmp_sei[i]; rep(i, fu) d_fu[i] = tmp_fu[i]; //大きくなるように sort(d_sei.begin(), d_sei.end()); //小さくなるように sort(d_fu.begin(), d_fu.end(), greater<int>()); int ans = 10000000; int sum; if (fu >= n - zero){ //負だけからとる時 sum = d_fu[n - zero - 1] * -1; ans = min(ans, sum); } if(sei >= n - zero){ //正だけからとる時 sum = d_sei[n - zero - 1]; ans = min(ans, sum); } //両方から取る時 reps(i, 1 , n - zero) //i個 { if(0 <=i - 1 && i - 1 <= fu - 1 && 0 <= n - i - 1 && n - i - 1 <= sei){ if (d_fu[i - 1] <= d_sei[n - i - 1]){ sum = d_fu[i - 1] * -2 + d_sei[n - i - 1]; }else{ sum = (d_fu[i - 1] * -1 + d_sei[n - i - 1] * 2); } ans = min(ans, sum); } } printf("%d\n", ans); return 0; }