diff --git a/003.py b/003.py
new file mode 100644
index 0000000..1a84df1
--- /dev/null
+++ b/003.py
@@ -0,0 +1,22 @@
+#문제 003 구간합 구하기1 43
+import sys
+
+
+input = sys.stdin.readline
+a,b = map(int,input().split())
+list = list(map(int,input().split()))
+
+#합배열 만들기
+[5,4,3,2,1]
+
+sum_li = [0]
+temp = 0
+
+for i in list:
+    
+    temp += i 
+    sum_li.append(temp)
+
+for i in range(b):
+    c,d = map(int,input().split())
+    print(sum_li[d] - sum_li[c])
\ No newline at end of file
diff --git a/006.py b/006.py
new file mode 100644
index 0000000..6e72b12
--- /dev/null
+++ b/006.py
@@ -0,0 +1,17 @@
+n = int(input())
+count = 1
+start_index = 1
+end_index = 1
+sum = 1
+while end_index != n:
+    if sum == n:
+        count += 1
+        end_index += 1
+        sum += end_index
+    elif sum > n:
+        sum -= start_index
+        start_index += 1
+    else:
+        end_index += 1
+        sum += end_index
+print(count)
\ No newline at end of file
diff --git a/007.py b/007.py
new file mode 100644
index 0000000..8741eb5
--- /dev/null
+++ b/007.py
@@ -0,0 +1,19 @@
+import sys
+input = sys.stdin.readline
+N = int(input());
+M = int(input());
+A = list(map(int, input().split()))
+A.sort()
+count = int(0)
+i = int(0)
+j = int(N-1)
+while i < j:    # 투 포인터 이동 원칙 따라 포인터를 이동하며 처리
+    if A[i] + A[j] < M:
+        i += 1
+    elif A[i] + A[j] > M:
+        j -= 1
+    else:
+        count += 1
+        i += 1
+        j -= 1
+print(count)
\ No newline at end of file