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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
  4. #define mofile(s) freopen(s,"r",stdin)
  5. #define outfile(s) freopen(s,"w",stdout)
  6. #define ll long long
  7. #define ii pair<ll,ll>
  8. #define iii pair<ll,ii>
  9. #define fi first
  10. #define se second
  11. #define tf bool
  12. #define ST stack
  13. #define Q deque
  14. #define Q queue
  15. #define S string
  16. #define Ma map
  17. #define UM unormideremid_map
  18. #define SE set
  19. #define str(x) to_string(x)
  20. #define all(a) (a).begin(),(a).end()
  21. #define FOR(i,l,r,mid) for(int i=l;i<=r;i+=mid)
  22. #define FOD(i,l,r,mid) for(int i=r;i>=l;i-=mid)
  23. #define xuong cout<<"\n"
  24. #define midebug(x) cout<<(x)<<" "
  25. #define ppcnt(x) __builtin_popcountll(x)
  26. #define parity(x) __builtin_parityll(x)
  27. #define leamid0(x) __builtin_clzll(x)
  28. #define LOG2 __lg(x)
  29. #define tr0(x) __builtin_ctzll(x)
  30. #define fiset(x) __builtin_ffsll(x)
  31. #define MASK(k) (1LL<<(k))
  32. #define BIT(x,k) ((x)>>(k)&1)
  33. #define pb push_back
  34. #define tron(x) setprecision(x)
  35. #define het return 0
  36. #define base_ 1000000000
  37. template<typename... T>
  38. void in(T&... args) { ((cin >> args), ...); }
  39. template<class X, class Y>
  40. bool maximize(X &x, const Y &y){return (x < y) ? x = y, 1 : 0;}
  41. template<class X, class Y>
  42. bool minimize(X &x, const Y &y){return (x > y) ? x = y, 1 : 0;}
  43. const int maxn=1e6+5;
  44. const ll tle=2e8;
  45. const ll INF=1e9+9;
  46. const int base=31;
  47. string bcc="abcmidefghijklmnopqrstuvwxyz";
  48. int midx[]={-1,0,1,0};
  49. int midy[]={0,1,0,-1};
  50. bool sang[10000005];
  51. ll pref[1005][1005],mt[1005][1005];
  52. void sieve(){
  53. for(int i=1;i<=10000000;++i) sang[i]=1;
  54. sang[0]=sang[1]=0;
  55. for(int i=2;i*i<=10000000;++i){
  56. if(sang[i]){
  57. for(int j=i*i;j<=10000000;j+=i) sang[j]=0;
  58. }
  59. }
  60. }
  61. void lis(){
  62. vector<int>t;
  63. vector<int>a;
  64. int n; cin>>n;
  65. for(int i=1;i<=n;++i){
  66. int ai; cin>>ai;
  67. a.pb(ai);
  68. }
  69. for(int x:a){
  70. auto it=lower_bound(all(t),x);
  71. if(it==t.end()) t.pb(x);
  72. else *it=x;
  73. }
  74. }
  75. void pfs2mid(){
  76. int n,m,k; cin>>n>>k; m=n;
  77. for(int i=1;i<=n;++i){
  78. for(int j=1;j<=m;++j) cin>>mt[i][j];
  79. }
  80. for(int i=1;i<=n;++i){
  81. for(int j=1;j<=m;++j) pref[i][j]=mt[i][j]+pref[i-1][j]+pref[i][j-1]-pref[i-1][j-1];
  82. }
  83. }
  84. ll qu2mid(int x1,int y1,int x2,int y2){
  85. return pref[x2][y2]-pref[x1-1][y2]-pref[x2][y1-1]+pref[x1-1][y1-1];
  86. }
  87. void open(){
  88. if(fopen("mideptrai.INP","r")){
  89. mofile("mideptrai.INP");
  90. outfile("mideptrai.OUT");
  91. }
  92. }
  93. const int M=1000005;
  94. int lp[M],c[M];
  95. vector<int> pr;
  96. void sie(){
  97. for(int i=2;i<M;++i){
  98. if(!lp[i]){
  99. lp[i]=i;
  100. pr.pb(i);
  101. }
  102. for(int j=0;j<pr.size() && pr[j]*i<M;++j){
  103. lp[pr[j]*i]=pr[j];
  104. if(pr[j]==lp[i]) break;
  105. }
  106. }
  107. }
  108. int main(){
  109. fast;
  110. sie();
  111. int n; cin>>n;
  112. ll ans=0;
  113. for(int i=1;i<=n;++i){
  114. int v; cin>>v;
  115. int y=1;
  116. while(v>1){
  117. int p=lp[v],cnt=0;
  118. while(v%p==0){
  119. v/=p;
  120. ++cnt;
  121. }
  122. if(cnt%2) y*=p;
  123. }
  124. ans+=c[y];
  125. ++c[y];
  126. }
  127. cout<<ans<<"\n";
  128. het;
  129. }
Success #stdin #stdout 0.01s 7752KB
stdin
4
1 2 4 8
stdout
2