#include #include #define GT(variableName, defaultValue, limit) for(int variableName = defaultValue; variableName < (int)limit; variableName++) #define GTE(variableName, defaultValue, limit) for(int variableName = defaultValue; variableName <= (int)limit; variableName++) #define LT(variableName, defaultValue, limit) for(int variableName = defaultValue; variableName > (int)limit; variableName--) #define LTE(variableName, defaultValue, limit) for(int variableName = defaultValue; variableName >= (int)limit; variableName--) #define YES cout << "Yes" << endl; #define NO cout << "No" << endl; using namespace std ; int main(){ long long N, X, answer; cin >> N >> X; answer = 0; vector a(N); GT(i, 0, N){ cin >> a[i]; } GT(i, 0, N){ GT(j, 0, N){ if(a[i] + a[j] == X){ answer++; } } } cout << answer << endl; }