#define _GLIBCXX_DEBUG
#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;
using ll = long long;
using ull = unsigned long long;
ull N, K;
unsigned P;
ull Solve(int x, vector<unsigned> A, vector<unsigned> B){
    unsigned a, b, c;
    a = (B[0] <= x) ? distance(A.begin(), upper_bound(A.begin(), A.end(), x - B[0])) : 0;
    b = distance(A.begin(), lower_bound(A.begin(), A.end(), P - B[0]));
    c = distance(A.begin(), upper_bound(A.begin(), A.end(), P + x - B[0]));
    ull ret = a + c - b;
    for (unsigned i = 1; i < N; i++){
        while(a > 0 && A[a-1] + B[i] > x ) a--;
        while(b > 0 && A[b-1] + B[i] >= P) b--;
        while(c > 0 && A[c-1] + B[i] > x + P) c--;
        ret += a + c - b;
    }
    return ret;
}

int main(){
    scanf("%llu %llu %u", &N, &K, &P);
    vector<unsigned> A(N);
    for(int i = 0; i < N; ++i) scanf("%u", &A[i]);
    sort(A.begin(), A.end());
    vector<unsigned> B(N);
    for(int i = 0; i < N; ++i) scanf("%u", &B[i]);
    sort(B.begin(), B.end());
    int ok = P-1, ng = -1, mid;
    while(ok - ng > 1){
        mid = ok + ng >>1;
        if(Solve(mid, A, B) >= K) ok = mid;
        else ng = mid;
    }
    printf("%d\n", ok);
	return 0;
}