import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const numCases = readInt;
      foreach (caseId; 0 .. numCases) {
        const N = readInt;
        const M = readInt;
        const K = readLong;
        auto X = new int[M];
        auto Y = new long[M];
        foreach (i; 0 .. M) {
          X[i] = readInt - 1;
          Y[i] = readLong;
        }
        
        /*
          \Delta[b] (b - Y)^2
          = 2 (b - Y) + 1
        */
        auto ps = new long[N];
        auto qs = new long[N];
        foreach (i; 0 .. M) {
          ps[X[i]] += 2;
          qs[X[i]] += -2 * Y[i] + 1;
        }
        
        // p b + q <= thr
        auto bs = new long[N];
        long check(long thr) {
          long sum;
          foreach (j; 0 .. N) {
            if (ps[j] == 0) {
              bs[j] = (0 <= thr) ? K : 0;
            } else {
              bs[j] = (thr - qs[j] >= 0) ? ((thr - qs[j]) / ps[j] + 1) : 0;
            }
            sum += bs[j];
          }
          return sum;
        }
        
        long lo = qs.sum - 1;
        long hi = ps.sum * K + 1;
        for (; lo + 1 < hi; ) {
          const mid = (lo + hi) / 2;
          ((check(mid) <= K) ? lo : hi) = mid;
        }
        long rem = K - check(lo);
        debug {
          writeln("lo = ", lo);
          writeln("bs = ", bs);
          writeln("rem = ", rem);
          foreach (j; 0 .. N) {
            // writeln(iota(K).map!(b => ps[j] * b + qs[j]));
          }
        }
        foreach (j; 0 .. N) {
          for (; rem > 0 && ps[j] * bs[j] + qs[j] == hi; ) {
            --rem;
            ++bs[j];
          }
        }
        assert(rem == 0);
        debug {
          writeln("bs = ", bs);
        }
        
        long ans;
        foreach (i; 0 .. M) {
          ans += (bs[X[i]] - Y[i])^^2;
        }
        writeln(ans);
      }
    }
  } catch (EOFException e) {
  }
}