import java.io.IOException; import java.io.InputStream; import java.math.BigInteger; import java.util.Arrays; import java.util.Comparator; import java.util.NoSuchElementException; public class Main { public static void main(String[] args) { new Main().run(); } final long[] MOD= {980000023,980000029}; //,980000033 long[][] ip26=new long[MOD.length][(int)3e5]; { for (int i=0;i=n||l>r) return 0; int ok=0; int ng=Math.min(l+2, (n-1-r)+2); while (ng-ok>1) { int middle=(ok+ng)/2; boolean ret=true; for (int j=0;j=0;--j) { hash1[i][j]=(j==n-1?0:hash1[i][j+1])+(int)(cs[j]-'a')*x; hash1[i][j]%=MOD[i]; x=x*26%MOD[i]; } } int ans=0; for (int i=0;i2*Math.min(i+1, n-i)) continue; int len=f(i,i+1,hash0,hash1); int even=2*len+2*Math.max(f(i-len-1,i+1+len,hash0,hash1),f(i-len,i+1+len+1,hash0,hash1)); len=f(i,i,hash0,hash1); int odd=2*len-1+2*Math.max(f(i-len-1,i+len,hash0,hash1),f(i-len,i+len+1,hash0,hash1)); if (odd==n) odd-=2; if (even==n) even-=2; ans=Math.max(ans,Math.max(odd, even)); } System.out.println(ans); } void tr(Object...objects) {System.out.println(Arrays.deepToString(objects));} } class FastScanner { private final InputStream in = System.in; private final byte[] buffer = new byte[1024]; private int ptr = 0; private int buflen = 0; private boolean hasNextByte() { if (ptr < buflen) { return true; }else{ ptr = 0; try { buflen = in.read(buffer); } catch (IOException e) { e.printStackTrace(); } if (buflen <= 0) { return false; } } return true; } private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;} private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;} private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;} public boolean hasNext() { skipUnprintable(); return hasNextByte();} public String next() { if (!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int b = readByte(); while(isPrintableChar(b)) { sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } public long nextLong() { if (!hasNext()) throw new NoSuchElementException(); long n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) { throw new NumberFormatException(); } while(true){ if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; }else if(b == -1 || !isPrintableChar(b)){ return minus ? -n : n; }else{ throw new NumberFormatException(); } b = readByte(); } } public int nextInt() { return (int)nextLong(); } }