import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    String A = sc.next();
    String B = sc.next();
    long ans = 0;
    long t = 0;
    for(int i = 1; i < A.length(); i++) {
      if((A.charAt(i) == '2') && (A.charAt(i - 1) == '1')) t++;
    }
    ans = (func(B) - func(A)) + t + (func2(B) - func2(A));
    System.out.println(ans); 
  }

  public static long func(String X) {
    int len = X.length();
    long[][][][] dp = new long[len][8][10][2];
    int first = Integer.parseInt(String.valueOf(X.charAt(0)));
    for(int i = 0; i < first; i++) {
      dp[0][0][i][1] = 1;
    }
    dp[0][0][first][0] = 1;
    
    for(int i = 1; i < len; i++) {
      int d = Integer.parseInt(String.valueOf(X.charAt(i)));
      for(int j = 0; j < 8; j++) {
        for(int l = 0; l <= d; l++) {
          if(l == d) {
            if(l == 2) {
              dp[i][j + 1][l][0] += dp[i - 1][j][1][0];
            } else {
              dp[i][j][l][0] += dp[i - 1][j][1][0];
            }
          } else {
            if(l == 2) {
              dp[i][j + 1][l][1] += dp[i - 1][j][1][0];
            } else {
              dp[i][j][l][1] += dp[i - 1][j][1][0];
            }
          }
        }
        for(int l = 0; l <= 9; l++) {
          if(l == 2) {
            dp[i][j + 1][l][1] += dp[i - 1][j][1][1];
          } else {
            dp[i][j][l][1] += dp[i - 1][j][1][1];
          }
        }
        for(int k = 0; k <= 9; k++) {
        if(k != 1) {
        for(int l = 0; l <= d; l++) {
          if(l == d) {
            dp[i][j][l][0] += dp[i - 1][j][k][0];
          } else {
            dp[i][j][l][1] += dp[i - 1][j][k][0];
          }
        }
        for(int l = 0; l <= 9; l++) {
          dp[i][j][l][1] += dp[i - 1][j][k][1];
        }
        }
        }      
      }
    }

    long ret = 0;
    for(int j = 1; j < 8; j++) {
      for(int k = 0; k <= 9; k++) {
        for(int l = 0; l < 2; l++) {
          ret += dp[len - 1][j][k][l];
        }
      }
    }

    return ret;
  }

  public static long func2(String X) {
    int len = X.length();
    long ret = 0;
    for(int i = 1; i < len; i++) {
      if(i == 1) {
        ret++;
      } else {
        ret += ((long)Math.pow(10, i - 2));
      }
    }
    int first = Integer.parseInt(String.valueOf(X.charAt(0)));
    if(first == 2) {
      int last = Integer.parseInt(String.valueOf(X.charAt(len - 1)));
      long t = Long.parseLong(X.substring(1, len - 1));
      if(last < 2) {
        ret += t;
      } else {
        ret += (t + 1);
      }
    }
    if(first > 2) {
      ret += ((long)Math.pow(10, len - 2));
    }
    if(X.equals("1")) {
      ret = 0;
    } else {
      if(len == 1) ret = 1;
    }
    return ret;
  }
}