read N
read -a arr

# We create the variable found to help us iterate
found=0
while [[ ${#arr[@]} -gt 1 ]]; do
    # We create an array with the existent indexes
    idx=()
    for i in ${!arr[@]}; do
        idx+=("$i")
    done
    
    # We pick the first value
    check=${arr[${idx[$found]}]}
    
    # We start the counter of matches
    count=0
    
    # We check the array counting matches
    for i in ${!arr[@]}; do
        if [[ "${arr[$i]}" -eq "$check" ]]; then
            ((count++))
        fi
    done
    
    # We check how many matches we have
    if [[ $count -eq 2 ]]; then
        # If we have 2 matcher, we delete ALL matches
        for i in ${!arr[@]}; do
            if [[ "${arr[$i]}" -eq "$check" ]]; then
                unset arr[$i]
            fi
        done
    else
        # Else, we have 1 match, aka the lonely integer
        # We increase the found, so the check value skips the one
        ((found++))
    fi
done
echo "${arr[@]}"