=m : n=i break print("N :",n)"> =m : n=i break print("N :",n)"> =m : n=i break print("N :",n)"> 
m=int(input("M : "))
s=0
n=0
for i in range(1,m+1):
    s+=i
    if s>=m :
        n=i
        break
print("N :",n)