N = int(input())
A = list(map(int, input().split())) 
A = A+[A[0]]
S = input()
L = []
for i in range(N):
    if A[i]<A[i+1]:
        L.append('<')
    else:
        L.append('>')
L  = ''.join(map(str, L))
L = L*2

if S in L:
    print(L.index(S))
else:
    print(-1)