Description
Nicholas, a painter is going to paint several new canvases. Nicholas is sure that the canvases will turn out so great that each one will need framing and being hung on the wall. Frames are what Nicholas decided to begin with.
Nicholas has n sticks whose lengths equal a1, a2, ...an. Nicholas does not want to break the sticks or glue them together. To make ah × w-sized frame, he needs two sticks whose lengths equalh and two sticks whose lengths equal w. Specifically, to make a square frame (when h = w), he needs four sticks of the same length.
Now Nicholas wants to make from the sticks that he has as many frames as possible; to be able to paint as many canvases as possible to fill the frames. Help him in this uneasy task. Note that it is not necessary to use all the sticks Nicholas has.
Input
The first line contains an integern (1 ≤ n ≤ 100) — the number of sticks. The second line containsn space-separated integers. The i-th integer equals the length of the i-th stickai (1 ≤ ai ≤ 100).
Output
Print the single number — the maximum number of frames Nicholas can make for his future canvases.
Sample Input
Input
52 4 3 2 3
Output
1
Input
132 2 4 4 4 4 6 6 6 7 7 9 9
Output
3
Input
43 3 3 5
Output
0
#include<stdio.h> int main() { int n; int i,j; int a[102]={0}; int count,count1; int k; scanf("%d",&n); for(i=0;i<n;i++) { scanf("%d",&a[i]); } count=0; while(n) { k=a[0]; count1=1; for(i=0;i<n-1;i++) { a[i]=a[i+1]; } n--; for(i=0;i<=n-1;i++) { if(a[i]==k) { for(j=i;j<n-1;j++) { a[j]=a[j+1]; } n--; count1++; i--; } } count+=count1/2;
} count=count/2; printf("%d\n",count); return 0; }
