Mean,Median and Mode

pairs.py

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+#count no of pairs of elements in a given list whose sum is equal to given sum 
+x=input().split(' ')
+n=int(x[0])    #no of elements of list
+s=int(x[1])    #required sum
+count=0
+b=[]
+a=input().split(' ')
+for i in range(n):
+    f=0
+    for j in range(n):
+        if(int(a[i])+int(a[j])==s):
+            f=1
+            p=a[i]
+            q=a[j]
+            break
+    if(f==1):
+        if(p not in b and q not in b):
+            b.append(p)
+            b.append(q)
+            count=count+1
+print(count)      #no of pairs
+
+