def z_algorithm(s):
    if not s: return []
    n = len(s); z = [0]*n; z[0] = n; i = 1; j = 0
    while i<n:
        while i+j<n and s[j]==s[i+j]: j += 1
        if not j: i += 1; continue
        z[i] = j; k = 1
        while i+k<n and k+z[k]<j: z[i+k] = z[k]; k += 1
        i += k; j -= k
    return z
for _ in range(int(input())):
    n = int(input()); s = input()
    z = z_algorithm(s); ans = 0
    for i in range(1,n):
        v = min(z[i],i)
        if i+v!=n and (v==i or s[v]<s[i+v]): ans += 1
    print(ans)