#include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int t;     cin >> t;     string cnv;     cnv.reserve(62);     for (char i =  a ; i <=  z ; ++i) {       cnv.push_back(i);     }     for (char i =  A ; i <=  Z ; ++i) {       cnv.push_back(i);     }     for (char i =  0 ; i <=  9 ; ++i) {       cnv.push_back(i);     }     for (int i = 0; i < t; ++i) {       int n, m, k;       cin >> n >> m >> k;       vector<string> mas(n);       int cnt = 0;       for (int j = 0; j < n; ++j) {         cin >> mas[j];         for (char c : mas[j]) {           cnt += (c ==  R );         }       }       int cur = 0;       int perc = cnt / k;       int bigger = cnt % k;       int curcnt = 0;       for (int i = 0; i < n; ++i) {         if (i & 1) {           for (int j = 0; j < m; ++j) {             if (mas[i][j] ==  R  && curcnt == perc + (cur < bigger)) {               ++cur;               curcnt = 0;             }             if (mas[i][j] ==  R ) ++curcnt;             mas[i][j] = cnv[cur];           }         } else {           for (int j = m - 1; j >= 0; --j) {             if (mas[i][j] ==  R  && curcnt == perc + (cur < bigger)) {               ++cur;               curcnt = 0;             }             if (mas[i][j] ==  R ) ++curcnt;             mas[i][j] = cnv[cur];           }         }       }       for (int i = 0; i < n; ++i) {         cout << mas[i] <<   n ;       }     }     return 0;   }   