def compute_prefix_function(pattern):
    m = len(pattern)
    prefix = [0] * m
    k = 0  # length of the previous longest prefix suffix
    for q in range(1, m):
        while k > 0 and pattern[k] != pattern[q]:
            k = prefix[k-1]
        if pattern[k] == pattern[q]:
            k += 1
        prefix[q] = k
    return prefix

def kmp_search(text, pattern, prefix):
    n = len(text)
    m = len(pattern)
    q = 0  # current index in pattern
    positions = []
    for i in range(n):
        while q > 0 and pattern[q] != text[i]:
            q = prefix[q-1]
        if pattern[q] == text[i]:
            q += 1
        if q == m:
            positions.append(i - m + 1)
            q = prefix[q-1]  # look for next possible match
    return positions

def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    N = int(input[idx])
    idx += 1
    A = list(map(int, input[idx:idx+N]))
    idx += N
    S = input[idx].strip()
    
    if len(S) != N-1:
        print(-1)
        return
    
    # Generate the 'rel' array
    rel = []
    for i in range(N):
        j = (i + 1) % N
        if A[i] < A[j]:
            rel.append('<')
        else:
            rel.append('>')
    
    # Text is rel concatenated twice
    T = rel + rel
    
    # Check if pattern is longer than N-1
    pattern = list(S)
    m = len(pattern)
    if m != N-1:
        print(-1)
        return
    
    # Compute prefix function for KMP
    prefix = compute_prefix_function(pattern)
    
    # Find all occurrences of pattern in T
    positions = kmp_search(T, pattern, prefix)
    
    # Check valid k (0 <= k < N)
    valid_ks = [k for k in positions if 0 <= k < N]
    
    if valid_ks:
        print(min(valid_ks))
    else:
        print(-1)

if __name__ == '__main__':
    main()