func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     int X = 0, w = 1;     char c = getchar();     while (c <  0  || c >  9 ) {       if (c ==  - ) w = -1;       c = getchar();     }     while (c >=  0  && c <=  9 ) X = X * 10 + c -  0 , c = getchar();     return X * w;   }   const int N = 1000 + 10;   int n, m, a[N];   double f[N][N];   int main() {     n = read(), m = read();     for (register int i = 1; i <= n; ++i) a[i] = read();     for (register int i = 1; i <= n; ++i)       for (register int j = 1; j <= n; ++j) f[i][j] = (a[i] > a[j]);     while (m--) {       int x = read(), y = read();       for (register int i = 1; i <= n; ++i) {         f[x][i] = f[y][i] = (f[x][i] + f[y][i]) / 2;         f[i][x] = f[i][y] = 1 - f[x][i];       }       f[x][y] = f[y][x] = 0.5;     }     double ans = 0;     for (register int i = 1; i <= n; ++i)       for (register int j = i + 1; j <= n; ++j) ans += f[i][j];     printf( %.9lf n , ans);     return 0;   }   