# # # # # for i in range(1,11):
# # # # #     print(i,end=" ")

# # # # l1= {1:"one",2:"two"}
# # # # print(type(l1))
# # # # for i in l1:
# # # #     print(f'{i} {l1[i]}')

# # # for i in "ASHISH":
# # #     print(i,end="")
# # # print("")

# # # for i in range():
# # #     print(i)

# sum=0
# print("enter the number for sum")
# inp=int(input())
# for i in range(inp+1):
#     sum += i
# # print(sum)

n=0
sum=0
while(n<6):
    sum+=n
    n+=1
print(sum)