func_code_string: #include <bits/stdc++.h>   using namespace std;   int seq[100];   int ans;   vector<string> in;   void solve(int k, int l) {     if (k <= l) {       vector<int> buf(in.size());       for (int i = 0; i < (int)in.size(); ++i) {         buf[i] = 0;       }       for (int i = 0; i < (int)in.size(); ++i) {         for (int j = 0; j < k; ++j) {           buf[i] += in[i][seq[j]] * pow(10, j);         }       }       sort(buf.begin(), buf.end());       ans = min(ans, *(buf.rbegin()) - *(buf.begin()));       return;     }     for (int i = 0; i < k; ++i) {       if (seq[i] < 0) {         seq[i] = l;         solve(k, l + 1);         seq[i] = -1;       }     }   }   int main(void) {     int n, k;     while (cin >> n >> k) {       ans = (100000000);       for (int i = 0; i < 100; ++i) {         seq[i] = -1;       }       in.clear();       in.resize(n);       for (int i = 0; i < n; ++i) {         cin >> in[i];       }       solve(k, 0);       cout << ans << endl;     }     return 0;   }   