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void main(){
List<int> nums = [1, 2, 3, 4, 5, 17, 6, 7, 8, 9, 6, 11, 10, 12, 13, 14, 2, 1, 4, 17, 4];
List repeated = [];
for(int i =0; i< nums.length; i++){
for(int j =0; j< nums.length; j++){
if ((nums[j]==nums[i]) && i != j){
if(repeated.contains(nums[i])){
continue;
}else{
repeated.add(nums[j]);
}
}
}
}
print(repeated);
}