let matchMap = {}
    let pairs = 0
    
    ar.forEach(num => {
        if (matchMap[num] === undefined) {
            matchMap[num] = 0
        }
        matchMap[num] += 1
    })
    for (const num in matchMap) {
        if (matchMap[num] > 1) {
           pairs += (Math.floor(matchMap[num] / 2)) 
        }
    }
    return pairs

int sockMerchant(int n, vector<int> ar) {
    map<int,int> socks;
    int pairsock=0;
    for (int i =0; i<n; i++) {
        socks[ar[i]]++;
    }
    for(auto &pair : socks){
        pairsock += pair.second/2;
    }
    return pairsock;
}

int sockMerchant(int n, vector<int> ar) {
    std::vector<bool> odds = std::vector<bool>(100);
    int nPairs = 0;
    for ( int sockID : ar ) {
        if ( odds[sockID-1] ) {
            nPairs++;
            odds[sockID-1] = false;
        } else {
            // odd sock found
            odds[sockID-1] = true;
        }
    }
    return nPairs;
}

function sockMerchant(n: number, ar: number[]): number {
   
   const socks = ar.sort((a,b)=>a-b);
   
   let result = 0;
   let last = socks[0];
   let pair = 0;
   
   for(let sock of socks) {
       if(sock === last) pair++;
       else { 
          result += pair%2 === 0 ? (pair)/2 : (pair-1)/2;
          
          pair = 1;
       }
           
       last = sock;
   }

   result += pair%2 === 0 ? (pair)/2 : (pair-1)/2;

   return result;
}

def sockMerchant(n, ar):
    return sum([ar.count(color)//2 for color in set(ar)])