# CFR 498 C. Array and Operations ( Flow )

Problem - 498C - Codeforces

u v：選一個 A[ u ] 和 A[ v ] 的公因數 g，進行 A[ u ] /= g, A[ v ] /= g，保證 ( u + v ) % 2 == 1

2 ≤ N ≤ 100
1 ≤ M ≤ 100
1 ≤ A[ i ] ≤ 1e9

u + v 是奇數這件事情明示了可以轉換成二分圖上的問題。

__對於偶數的一個點 x，從源點建弧，容量為可除以 v 的次數。
__對於奇數，對匯點，同理。

O( O( Dinic's ) )

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

template< class T >
struct Dinic {
static const int MAXV = 120;
static const T INF = 0x3f3f3f3f;
struct Edge {
int v;
T f;
int re;
Edge( int _v, T _f, int _re ): v( _v ), f( _f ), re( _re ) {}
};
int n, s, t, level[ MAXV ];
vector< Edge > E[ MAXV ];
int now[ MAXV ];
Dinic( int _n, int _s, int _t ): n( _n ), s( _s ), t( _t ) {}
void add_edge( int u, int v, T f, bool bidirectional = false ) {
E[ u ].emplace_back( v, f, E[ v ].size() );
E[ v ].emplace_back( u, 0, E[ u ].size() - 1 );
if( bidirectional ) {
E[ v ].emplace_back( u, f, E[ u ].size() - 1 );
}
}
bool BFS() {
memset( level, -1, sizeof( level ) );
queue< int > que;
que.emplace( s );
level[ s ] = 0;
while( not que.empty() ) {
int u = que.front();
que.pop();
for( auto it: E[ u ] ) {
if( it.f > 0 and level[ it.v ] == -1 ) {
level[ it.v ] = level[ u ] + 1;
que.emplace( it.v );
}
}
}
return level[ t ] != -1;
}
T DFS( int u, T nf ) {
if( u == t ) return nf;
T res = 0;
while( now[ u ] < E[ u ].size() ) {
Edge &it = E[ u ][ now[ u ] ];
if( it.f > 0 and level[ it.v ] == level[ u ] + 1 ) {
T tf = DFS( it.v, min( nf, it.f ) );
res += tf; nf -= tf; it.f -= tf;
E[ it.v ][ it.re ].f += tf;
if( nf == 0 ) return res;
} else ++now[ u ];
}
if( not res ) level[ u ] = -1;
return res;
}
T flow( T res = 0 ) {
while( BFS() ) {
T temp;
memset( now, 0, sizeof( now ) );
while( temp = DFS( s, INF ) ) {
res += temp;
res = min( res, INF );
}
}
return res;
}
};

const int MAXN = 100;
const int MAXM = 100;

int N, M;
int A[ MAXN ];
int I[ MAXM ], J[ MAXM ];

set< int > all_fac;

void update_fac( set< int > &bag, int v ) {
int _ = v;
for( int i = 2; i * i <= _; ++i ) {
if( _ % i != 0 ) continue;
bag.emplace( i );
while( _ % i == 0 ) _ /= i;
}
if( _ != 1 ) bag.emplace( _ );
}

signed main() {
ios::sync_with_stdio( 0 );
cin >> N >> M;
for( int i = 0; i < N; ++i ) {
cin >> A[ i ];
update_fac( all_fac, A[ i ] );
}
for( int i = 0; i < M; ++i ) {
cin >> I[ i ] >> J[ i ];
--I[ i ], --J[ i ];
if( I[ i ] & 1 ) {
swap( I[ i ], J[ i ] );
}
}
long long ans = 0;
for( int v: all_fac ) {
int MAXNODE = 100;
int SOURCE = MAXNODE;
int SINK = MAXNODE + 1;
Dinic< int > din( MAXNODE + 2, SOURCE, SINK );
for( int i = 0; i < N; ++i ) {
int cnt = 0;
for( int j = A[ i ]; j % v == 0; j /= v, ++cnt ) ;
if( i & 1 ) {