Language: C++

#include <bits/stdc++.h>
using namespace std;

/*
    https://beta.atcoder.jp/contests/abc109/tasks/abc109_c
*/

#define li long long int
#define rep(i, to) for (li i = 0; i < ((li)(to)); i++)
#define repp(i, start, to) for (li i = (li)(start); i < ((li)(to)); i++)
#define pb push_back
#define sz(v) ((li)(v).size())
#define bgn(v) ((v).begin())
#define eend(v) ((v).end())
#define allof(v) (v).begin(), (v).end()
#define dodp(v, n) memset(v, (li)n, sizeof(v))
#define bit(n) (1ll << (li)(n))
#define mp(a, b) make_pair(a, b)
#define rin rep(i, n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1

#define idp if (DBGP)
#define F first
#define S second
#define p2(a, b) idp cout << a << "\t" << b << endl
#define p3(a, b, c) idp cout << a << "\t" << b << "\t" << c << endl
#define p4(a, b, c, d) idp cout << a << "\t" << b << "\t" << c << "\t" << d << endl
#define p5(a, b, c, d, e) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << endl
#define p6(a, b, c, d, e, f) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << endl
#define p7(a, b, c, d, e, f, g) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << "\t" << g << endl
#define p8(a, b, c, d, e, f, g, h) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << "\t" << g << "\t" << h << endl
#define p9(a, b, c, d, e, f, g, h, i) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << "\t" << g << "\t" << h << "\t" << i << endl
#define p10(a, b, c, d, e, f, g, h, i, j) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << "\t" << g << "\t" << h << "\t" << i << "\t" << j << endl
#define foreach(it, v) for (__typeof((v).begin()) it = (v).begin(); it != (v).end(); ++it)
#define p2p(x) idp p2((x).F, (x).S)
#define dump(x, n)                         \
    idp                                    \
    {                                      \
        rep(i, n) { cout << x[i] << " "; } \
        puts("");                          \
    }
#define dump2(x, n)                                                     \
    idp                                                                 \
    {                                                                   \
        rep(i, n) { cout << "[" << x[i].F << " , " << x[i].S << "] "; } \
        puts("");                                                       \
    }
#define dumpi(x)                  \
    idp                           \
    {                             \
        foreach (it, x)           \
        {                         \
            cout << (*it) << " "; \
        }                         \
        puts("");                 \
    }
#define dumpi2(x)                                               \
    idp                                                         \
    {                                                           \
        foreach (it, x)                                         \
        {                                                       \
            cout << "[" << (it)->F << " , " << (it)->S << "] "; \
        }                                                       \
        puts("");                                               \
    }

#define read2d(a, w, h) rep(i, h) rep(j, w) cin >> a[i][j]
#define dump2d(a, w, h)                   \
    rep(i, h)                             \
    {                                     \
        rep(j, w) cout << a[i][j] << " "; \
        puts("");                         \
    }

typedef pair<li, li> PI;

li v[100100];
li x[100100];

PI dp1[100100];
PI dp2[100100];

li a, b, c;
string s;

li gcd( li m, li n )
{
    while( m != n )
    {
        if ( m > n ){
            m = m - n;
        } else {
            n = n - m;
        }
    }
    return m;
}

li solve() {
    li ans = v[0];
    rep(i, a - 1){
         ans = gcd(ans, v[i + 1]);
         if(ans == 1){
            break;
         }
    }
    return ans;
}

#include <bits/stdc++.h>
using namespace std;

/*
    https://beta.atcoder.jp/contests/abc109/tasks/abc109_c
*/

#define li long long int
#define rep(i, to) for (li i = 0; i < ((li)(to)); i++)
#define repp(i, start, to) for (li i = (li)(start); i < ((li)(to)); i++)
#define pb push_back
#define sz(v) ((li)(v).size())
#define bgn(v) ((v).begin())
#define eend(v) ((v).end())
#define allof(v) (v).begin(), (v).end()
#define dodp(v, n) memset(v, (li)n, sizeof(v))
#define bit(n) (1ll << (li)(n))
#define mp(a, b) make_pair(a, b)
#define rin rep(i, n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1

#define idp if (DBGP)
#define F first
#define S second
#define p2(a, b) idp cout << a << "\t" << b << endl
#define p3(a, b, c) idp cout << a << "\t" << b << "\t" << c << endl
#define p4(a, b, c, d) idp cout << a << "\t" << b << "\t" << c << "\t" << d << endl
#define p5(a, b, c, d, e) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << endl
#define p6(a, b, c, d, e, f) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << endl
#define p7(a, b, c, d, e, f, g) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << "\t" << g << endl
#define p8(a, b, c, d, e, f, g, h) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << "\t" << g << "\t" << h << endl
#define p9(a, b, c, d, e, f, g, h, i) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << "\t" << g << "\t" << h << "\t" << i << endl
#define p10(a, b, c, d, e, f, g, h, i, j) idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t" << f << "\t" << g << "\t" << h << "\t" << i << "\t" << j << endl
#define foreach(it, v) for (__typeof((v).begin()) it = (v).begin(); it != (v).end(); ++it)
#define p2p(x) idp p2((x).F, (x).S)
#define dump(x, n)                         \
    idp                                    \
    {                                      \
        rep(i, n) { cout << x[i] << " "; } \
        puts("");                          \
    }
#define dump2(x, n)                                                     \
    idp                                                                 \
    {                                                                   \
        rep(i, n) { cout << "[" << x[i].F << " , " << x[i].S << "] "; } \
        puts("");                                                       \
    }
#define dumpi(x)                  \
    idp                           \
    {                             \
        foreach (it, x)           \
        {                         \
            cout << (*it) << " "; \
        }                         \
        puts("");                 \
    }
#define dumpi2(x)                                               \
    idp                                                         \
    {                                                           \
        foreach (it, x)                                         \
        {                                                       \
            cout << "[" << (it)->F << " , " << (it)->S << "] "; \
        }                                                       \
        puts("");                                               \
    }

#define read2d(a, w, h) rep(i, h) rep(j, w) cin >> a[i][j]
#define dump2d(a, w, h)                   \
    rep(i, h)                             \
    {                                     \
        rep(j, w) cout << a[i][j] << " "; \
        puts("");                         \
    }

typedef pair<li, li> PI;

li v[100100];
li x[100100];

PI dp1[100100];
PI dp2[100100];

li a, b, c;
string s;

li gcd(li m,li n){return n?gcd(m,m%n):m;}
li solve() {
    li ans = v[0];
    rep(i, a - 1){
         
         ans = ans < v[i + 1] ? gcd(ans, v[i + 1]) : gcd(v[i + 1], ans);
         if(ans == 1){
            break;
         }
    }
    return ans;
}

int main(void) {
    cin >> a >> b;

    li tmp;
    rep(i, a){
        cin >> tmp;
        tmp = abs(tmp - b);
        v[i] = tmp;
    }
    cout << solve() << endl;
    return 0;
}

Compiler output:
a.cc:200:4: error: redefinition of 'long long int v [100100]'
  200 | li v[100100];
      |    ^
a.cc:84:4: note: 'long long int v [100100]' previously declared here
   84 | li v[100100];
      |    ^
a.cc:201:4: error: redefinition of 'long long int x [100100]'
  201 | li x[100100];
      |    ^
a.cc:85:4: note: 'long long int x [100100]' previously declared here
   85 | li x[100100];
      |    ^
a.cc:203:4: error: redefinition of 'PI dp1 [100100]'
  203 | PI dp1[100100];
      |    ^~~
a.cc:87:4: note: 'PI dp1 [100100]' previously defined here
   87 | PI dp1[100100];
      |    ^~~
a.cc:204:4: error: redefinition of 'PI dp2 [100100]'
  204 | PI dp2[100100];
      |    ^~~
a.cc:88:4: note: 'PI dp2 [100100]' previously defined here
   88 | PI dp2[100100];
      |    ^~~
a.cc:206:4: error: redefinition of 'long long int a'
  206 | li a, b, c;
      |    ^
a.cc:90:4: note: 'long long int a' previously declared here
   90 | li a, b, c;
      |    ^
a.cc:206:7: error: redefinition of 'long long int b'
  206 | li a, b, c;
      |       ^
a.cc:90:7: note: 'long long int b' previously declared here
   90 | li a, b, c;
      |       ^
a.cc:206:10: error: redefinition of 'long long int c'
  206 | li a, b, c;
      |          ^
a.cc:90:10: note: 'long long int c' previously declared here
   90 | li a, b, c;
      |          ^
a.cc:207:8: error: redefinition of 'std::string s'
  207 | string s;
      |        ^
a.cc:91:8: note: 'std::string s' previously declared here
   91 | string s;
      |        ^
a.cc:209:4: error: redefinition of 'long long int gcd(long long int, long long int)'
  209 | li gcd(li m,li n){return n?gcd(m,m%n):m;}
      |    ^~~
a.cc:93:4: note: 'long long int gcd(long long int, long long int)' previously defined here
   93 | li gcd( li m, li n )
      |    ^~~
a.cc:210:4: error: redefinition of 'long long int solve()'
  210 | li solve() {
      |    ^~~~~
a.cc:106:4: note: 'long long int solve()' previously defined here
  106 | li solve() {
      |    ^~~~~