import sys
input=sys.stdin.readline
s=int(input())
sum=0
cnt=0
for i in range(0, s):
sum+=i
if sum>s:
cnt=i-1
break
elif sum==s:
cnt=i
break
if s==1 or s==2:
print(1)
else:
print(cnt)
import sys
input=sys.stdin.readline
s=int(input())
i=1
while True:
s-=i
if s==0:
print(i)
break
elif s<0:
print(i-1)
break
i+=1
import sys
input=sys.stdin.readline
s=int(input())
k=1
sum=0
while True:
sum+=k
if sum>=s:
# print(sum, k)
break
k+=1
if sum>s:
print(k-1)
else:
print(k)
1
s = int(input())
k = 0
j = 0
while(s>k):
j += 1
k += j
if (k>s):
j -= 1
print(j)
2
a = int(input())
i = 0
while a>=0:
i += 1
a -= i
print(i-1)
3 풀이참고
n = int(input())
i = 0
cnt = 0
while True:
if n > i: # n이 i보다 크면 n에 i를 차감
i += 1
n = n-i
cnt += 1
else:
print(cnt)
break