import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }

string COLOR(string s = "") { return "\x1b[" ~ s ~ "m"; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const N = readInt;
      auto A = new int[2 * N];
      foreach (i; 0 .. N) {
        A[i] = readInt;
      }
      const S = readToken;
      
      A[N .. 2 * N] = A[0 .. N];
      
      auto fail = new int[N];
      {
        int j = fail[0] = -1;
        foreach (i; 0 .. N - 1) {
          for (; ~j && S[j] != S[i]; j = fail[j]) {}
          fail[i + 1] = ++j;
        }
      }
      
      int ans = -1;
      {
        int j;
        foreach (i; 1 .. 2 * N) {
          const b = (A[i - 1] < A[i]) ? '<' : '>';
          for (; ~j && S[j] != b; j = fail[j]) {}
          if (++j == N - 1) {
            ans = i - (N - 1);
            break;
          }
        }
      }
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}