odd=[]
natur = []
for i in range(1,1000001):
    natur.append(i)
for i in range(1,10000001):
    if(i%2==1):
        odd.append(i)
def sumOfGroup(k):
    S=0
    for i in range(k-1):
        S = S + natur[i]
    return sum(odd[S:S+k])

if __name__ == "__main__":
    k = int(input().strip())
    answer = sumOfGroup(k)
    print(answer)