diff --git a/binary search.c b/binary search.c
new file mode 100644
index 0000000..0f2dbe2
--- /dev/null
+++ b/binary search.c	
@@ -0,0 +1,36 @@
+#include<stdio.h>
+
+int binary_search(int a[],int l,int u,int choice)//assumes array is sorted 
+{
+	int m;
+	while(l<u)
+	{
+		m=(l+u)/2;
+
+		if(a[m]==choice)
+			return m;
+
+		if(choice<a[m])
+			u=m-1;
+		else
+			l=m+1;
+	}
+
+	if(a[l]==choice)
+		return l;
+	else
+		return -1;
+}
+
+int main()
+ {
+ 	int a[10]={1,2,2,3,4,5,6,7,8,9};
+
+ 	int c=binary_search(a,0,9,2);
+ 	if(c==-1)
+ 		printf("NON existing\n");
+ 	else
+ 		printf("EXISTING at index %d\n",c);
+ 	
+ 	return 0;
+ }
\ No newline at end of file
diff --git a/d_discrete.c b/d_discrete.c
new file mode 100644
index 0000000..7d9cdf5
--- /dev/null
+++ b/d_discrete.c
@@ -0,0 +1,28 @@
+	#include<stdio.h>
+
+	int main()
+	{
+		unsigned long long p,test,x,y,m,n;
+
+		scanf("%llu",&test);
+
+		for(;test>0;test--)
+		{
+			scanf("%llu%llu%llu",&x,&y,&m);
+			
+			x%=m;
+
+			p=1;
+
+		for(;y>0;y/=2)
+		{
+			if(y & 1)
+				p=(p*x)%m;
+
+			x=(x*x)%m;
+		}
+			printf("%llu ",p);
+		}
+
+		return 0;
+	}
\ No newline at end of file
diff --git a/e.c b/e.c
new file mode 100644
index 0000000..169ce9e
--- /dev/null
+++ b/e.c
@@ -0,0 +1,43 @@
+#include<stdio.h>
+#include<stdlib.h>
+int a[1001];
+int b[1001];
+
+int main()
+{
+	int n,x,count=0,i,t;
+	scanf("%d%d",&n,&x);
+
+	for(i=0;i<n;i++)
+	{
+		scanf("%d",&t);
+		if(t<0)
+		{
+			t*=(-1);
+			a[t]++;
+		}
+		else if (t>0)
+		{
+			/* code */
+			b[t]++;
+		}
+	}
+
+	for(i=1;i<=x;i++)
+	{
+		if(a[i]==b[i])
+			continue;
+		else
+		{
+			t=abs(a[i]-b[i]);
+			if(t<0)
+				t*=(-1);
+			count+=t;
+			//count+=abs(a[i]-b[i]);
+		}
+	}
+
+	printf("%d",count);
+
+	return 0;
+}
\ No newline at end of file