How to solve this generic vector member error in my LRUCache class?

Please have a look at my code sample. I am trying to create a LRUCache class to manage least recent cache. I am facing some vector errors in unexpected places. I do not know why I am having problems with vector v in my class. It is just a member variable inside my class:

..\src\lru.cpp: In instantiation of 'void LRUCache<K, V>::put(K, V) [with K 
= int; V = int]':
..\src\lru.cpp:70:20:   required from here
..\src\lru.cpp:57:20: error: request for member 'size' in 'v', which is of 
non-class type 'int'
   if(capacity == v.size()) { // vector v is full
                ~~^~~~

Here is my code:

template <class K, class V>
class LRUCache {

private:
  int capacity;
  vector<K> v;
  unordered_map<K, V> m;
  int findIndexOfK(K k);
public:
  LRUCache(int vcapacity) : capacity(vcapacity) {

  }
  V get(K k);
  void put(K k, V v);
};

template <class K, class V>
int LRUCache<K, V>::findIndexOfK(K k) {
    int index {-1};
    for(int i=0; i < capacity; i++) {
       if(v[i]==k) {
          index = i;
          break;
       }
    }
    return index;
}

template <class K, class V>
V LRUCache<K, V>::get(K k) {
    auto i = m.find(k);
    if(i == m.end()) {
        return -1;
    }
    else
        return i->second;
    }

template <class K, class V>
void LRUCache<K, V>::put(K k, V v) {
    int index = findIndexOfK(k);
    if(index == -1) {
        if(capacity == v.size()) { // vector v is full
            v.erase(v.begin()); // Remove the least recent one
        }
    }
    else {
        v.erase(v.begin()+index); // Remove the existing one whose index was found
    }
    m[k] = v;
    v.add(k);
}

int main() {
    LRUCache<int, int> lrucache(3);
    lrucache.put(2, 33);
    lrucache.put(5, 40);
    assert(lrucache.get(2) == 33);
    return 0;
}