左偏树

namespace lt {
    int ls[N], rs[N], siz[N], d[N], rt[N];
    LL val[N], sum[N];
    int merge(int x, int y) {
        if(!x || !y) return x | y;
        if(val[x] < val[y]) std::swap(x, y);
        rs[x] = merge(rs[x], y);
        if(d[rs[x]] > d[ls[x]]) std::swap(ls[x], rs[x]);
        d[x] = d[rs[x]] + 1;
        sum[x] = sum[ls[x]] + sum[rs[x]] + val[x];
        siz[x] = siz[ls[x]] + siz[rs[x]] + 1;
        return x;
    }
    inline void exmerge(int x, int y) { // y -> x
        rt[x] = merge(rt[x], rt[y]);
        return;
    }
    inline void pop(int x) {
        rt[x] = merge(ls[rt[x]], rs[rt[x]]);
        return;
    }
    inline int getSum(int x) {
        return sum[rt[x]];
    }
    inline int getSiz(int x) {
        return siz[rt[x]];
    }
    inline void init(int i, LL v) {
        val[i] = v;
        sum[i] = v;
        siz[i] = 1;
        d[i] = 1;
        rt[i] = i;
        return;
    }
}