class Solution {
public:
    int longestConsecutive(vector<int>& nums) {
        unordered_set<int>se;
        for(int x: nums)se.insert(x);
        int ans = 0;
        for(int x : se){
            if(!se.count(x-1)){
                int cur = x, cc = 1;
                while(se.count(cur+1))cur++,cc++;
                ans = max(ans, cc);
            }
        }
        return ans;
    }
};