func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long MAXN = 1e3 + 10;   long double dp[MAXN][MAXN];   long long p[MAXN];   int main() {     ios_base ::sync_with_stdio(false);     cin.tie(0);     cout << fixed << setprecision(10);     long long n, m;     cin >> n >> m;     long double res = 0;     for (long long i = 1; i <= n; i++) {       cin >> p[i];     }     for (long long i = 1; i <= n; i++) {       for (long long j = i + 1; j <= n; j++) {         dp[i][j] = (p[j] < p[i]);       }     }     for (long long i = 0; i < m; i++) {       long long a, b;       cin >> a >> b;       if (a > b) {         swap(a, b);       }       for (long long j = b + 1; j <= n; j++) {         long double e = (dp[a][j] + dp[b][j]) / 2;         dp[a][j] = e;         dp[b][j] = e;       }       for (long long j = a - 1; j >= 1; j--) {         long double e = (dp[j][a] + dp[j][b]) / 2;         dp[j][a] = e;         dp[j][b] = e;       }       for (long long j = a + 1; j < b; j++) {         long double e = dp[a][j], f = dp[j][b];         dp[a][j] = (1 + e - f) / 2;         dp[j][b] = (1 + f - e) / 2;       }       dp[a][b] = (long double)(1) / 2;     }     for (long long i = 1; i <= n; i++) {       for (long long j = i + 1; j <= n; j++) {         res += dp[i][j];       }     }     cout << res;   }   