Problem:
Score : 300 points

Problem Statement

2N players are running a competitive table tennis training on N tables numbered from 1 to N.

The training consists of rounds.
In each round, the players form N pairs, one pair per table.
In each pair, competitors play a match against each other.
As a result, one of them wins and the other one loses.

The winner of the match on table X plays on table X-1 in the next round,
except for the winner of the match on table 1 who stays at table 1.

Similarly, the loser of the match on table X plays on table X+1 in the next round,
except for the loser of the match on table N who stays at table N.

Two friends are playing their first round matches on distinct tables A and B.
Let's assume that the friends are strong enough to win or lose any match at will.
What is the smallest number of rounds after which the friends can get to play a match against each other?

Constraints

2 \leq N \leq 10^{18}

1 \leq A < B \leq N

All input values are integers.

Input

Input is given from Standard Input in the following format:

N A B

Output

Print the smallest number of rounds after which the friends can get to play a match against each other.

Sample Input 1

5 2 4

Sample Output 1

1

If the first friend loses their match and the second friend wins their match, they will both move to table 3 and play each other in the next round.

Sample Input 2

5 2 3

Sample Output 2

2

If both friends win two matches in a row, they will both move to table 1.

Solution in JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

var bigInt=function(undefined){"use strict";var BASE=1e7,LOG_BASE=7,MAX_INT=9007199254740992,MAX_INT_ARR=smallToArray(MAX_INT),DEFAULT_ALPHABET="0123456789abcdefghijklmnopqrstuvwxyz";var supportsNativeBigInt=typeof BigInt==="function";function Integer(v,radix,alphabet,caseSensitive){if(typeof v==="undefined")return Integer[0];if(typeof radix!=="undefined")return+radix===10&&!alphabet?parseValue(v):parseBase(v,radix,alphabet,caseSensitive);return parseValue(v)}function BigInteger(value,sign){this.value=value;this.sign=sign;this.isSmall=false}BigInteger.prototype=Object.create(Integer.prototype);function SmallInteger(value){this.value=value;this.sign=value<0;this.isSmall=true}SmallInteger.prototype=Object.create(Integer.prototype);function NativeBigInt(value){this.value=value}NativeBigInt.prototype=Object.create(Integer.prototype);function isPrecise(n){return-MAX_INT<n&&n<MAX_INT}function smallToArray(n){if(n<1e7)return[n];if(n<1e14)return[n%1e7,Math.floor(n/1e7)];return[n%1e7,Math.floor(n/1e7)%1e7,Math.floor(n/1e14)]}function arrayToSmall(arr){trim(arr);var length=arr.length;if(length<4&&compareAbs(arr,MAX_INT_ARR)<0){switch(length){case 0:return 0;case 1:return arr[0];case 2:return arr[0]+arr[1]*BASE;default:return arr[0]+(arr[1]+arr[2]*BASE)*BASE}}return arr}function trim(v){var i=v.length;while(v[--i]===0);v.length=i+1}function createArray(length){var x=new Array(length);var i=-1;while(++i<length){x[i]=0}return x}function truncate(n){if(n>0)return Math.floor(n);return Math.ceil(n)}function add(a,b){var l_a=a.length,l_b=b.length,r=new Array(l_a),carry=0,base=BASE,sum,i;for(i=0;i<l_b;i++){sum=a[i]+b[i]+carry;carry=sum>=base?1:0;r[i]=sum-carry*base}while(i<l_a){sum=a[i]+carry;carry=sum===base?1:0;r[i++]=sum-carry*base}if(carry>0)r.push(carry);return r}function addAny(a,b){if(a.length>=b.length)return add(a,b);return add(b,a)}function addSmall(a,carry){var l=a.length,r=new Array(l),base=BASE,sum,i;for(i=0;i<l;i++){sum=a[i]-base+carry;carry=Math.floor(sum/base);r[i]=sum-carry*base;carry+=1}while(carry>0){r[i++]=carry%base;carry=Math.floor(carry/base)}return r}BigInteger.prototype.add=function(v){var n=parseValue(v);if(this.sign!==n.sign){return this.subtract(n.negate())}var a=this.value,b=n.value;if(n.isSmall){return new BigInteger(addSmall(a,Math.abs(b)),this.sign)}return new BigInteger(addAny(a,b),this.sign)};BigInteger.prototype.plus=BigInteger.prototype.add;SmallInteger.prototype.add=function(v){var n=parseValue(v);var a=this.value;if(a<0!==n.sign){return this.subtract(n.negate())}var b=n.value;if(n.isSmall){if(isPrecise(a+b))return new SmallInteger(a+b);b=smallToArray(Math.abs(b))}return new BigInteger(addSmall(b,Math.abs(a)),a<0)};SmallInteger.prototype.plus=SmallInteger.prototype.add;NativeBigInt.prototype.add=function(v){return new NativeBigInt(this.value+parseValue(v).value)};NativeBigInt.prototype.plus=NativeBigInt.prototype.add;function subtract(a,b){var a_l=a.length,b_l=b.length,r=new Array(a_l),borrow=0,base=BASE,i,difference;for(i=0;i<b_l;i++){difference=a[i]-borrow-b[i];if(difference<0){difference+=base;borrow=1}else borrow=0;r[i]=difference}for(i=b_l;i<a_l;i++){difference=a[i]-borrow;if(difference<0)difference+=base;else{r[i++]=difference;break}r[i]=difference}for(;i<a_l;i++){r[i]=a[i]}trim(r);return r}function subtractAny(a,b,sign){var value;if(compareAbs(a,b)>=0){value=subtract(a,b)}else{value=subtract(b,a);sign=!sign}value=arrayToSmall(value);if(typeof value==="number"){if(sign)value=-value;return new SmallInteger(value)}return new BigInteger(value,sign)}function subtractSmall(a,b,sign){var l=a.length,r=new Array(l),carry=-b,base=BASE,i,difference;for(i=0;i<l;i++){difference=a[i]+carry;carry=Math.floor(difference/base);difference%=base;r[i]=difference<0?difference+base:difference}r=arrayToSmall(r);if(typeof r==="number"){if(sign)r=-r;return new SmallInteger(r)}return new BigInteger(r,sign)}BigInteger.prototype.subtract=function(v){var n=parseValue(v);if(this.sign!==n.sign){return this.add(n.negate())}var a=this.value,b=n.value;if(n.isSmall)return subtractSmall(a,Math.abs(b),this.sign);return subtractAny(a,b,this.sign)};BigInteger.prototype.minus=BigInteger.prototype.subtract;SmallInteger.prototype.subtract=function(v){var n=parseValue(v);var a=this.value;if(a<0!==n.sign){return this.add(n.negate())}var b=n.value;if(n.isSmall){return new SmallInteger(a-b)}return subtractSmall(b,Math.abs(a),a>=0)};SmallInteger.prototype.minus=SmallInteger.prototype.subtract;NativeBigInt.prototype.subtract=function(v){return new NativeBigInt(this.value-parseValue(v).value)};NativeBigInt.prototype.minus=NativeBigInt.prototype.subtract;BigInteger.prototype.negate=function(){return new BigInteger(this.value,!this.sign)};SmallInteger.prototype.negate=function(){var sign=this.sign;var small=new SmallInteger(-this.value);small.sign=!sign;return small};NativeBigInt.prototype.negate=function(){return new NativeBigInt(-this.value)};BigInteger.prototype.abs=function(){return new BigInteger(this.value,false)};SmallInteger.prototype.abs=function(){return new SmallInteger(Math.abs(this.value))};NativeBigInt.prototype.abs=function(){return new NativeBigInt(this.value>=0?this.value:-this.value)};function multiplyLong(a,b){var a_l=a.length,b_l=b.length,l=a_l+b_l,r=createArray(l),base=BASE,product,carry,i,a_i,b_j;for(i=0;i<a_l;++i){a_i=a[i];for(var j=0;j<b_l;++j){b_j=b[j];product=a_i*b_j+r[i+j];carry=Math.floor(product/base);r[i+j]=product-carry*base;r[i+j+1]+=carry}}trim(r);return r}function multiplySmall(a,b){var l=a.length,r=new Array(l),base=BASE,carry=0,product,i;for(i=0;i<l;i++){product=a[i]*b+carry;carry=Math.floor(product/base);r[i]=product-carry*base}while(carry>0){r[i++]=carry%base;carry=Math.floor(carry/base)}return r}function shiftLeft(x,n){var r=[];while(n-- >0)r.push(0);return r.concat(x)}function multiplyKaratsuba(x,y){var n=Math.max(x.length,y.length);if(n<=30)return multiplyLong(x,y);n=Math.ceil(n/2);var b=x.slice(n),a=x.slice(0,n),d=y.slice(n),c=y.slice(0,n);var ac=multiplyKaratsuba(a,c),bd=multiplyKaratsuba(b,d),abcd=multiplyKaratsuba(addAny(a,b),addAny(c,d));var product=addAny(addAny(ac,shiftLeft(subtract(subtract(abcd,ac),bd),n)),shiftLeft(bd,2*n));trim(product);return product}function useKaratsuba(l1,l2){return-.012*l1-.012*l2+15e-6*l1*l2>0}BigInteger.prototype.multiply=function(v){var n=parseValue(v),a=this.value,b=n.value,sign=this.sign!==n.sign,abs;if(n.isSmall){if(b===0)return Integer[0];if(b===1)return this;if(b===-1)return this.negate();abs=Math.abs(b);if(abs<BASE){return new BigInteger(multiplySmall(a,abs),sign)}b=smallToArray(abs)}if(useKaratsuba(a.length,b.length))return new BigInteger(multiplyKaratsuba(a,b),sign);return new BigInteger(multiplyLong(a,b),sign)};BigInteger.prototype.times=BigInteger.prototype.multiply;function multiplySmallAndArray(a,b,sign){if(a<BASE){return new BigInteger(multiplySmall(b,a),sign)}return new BigInteger(multiplyLong(b,smallToArray(a)),sign)}SmallInteger.prototype._multiplyBySmall=function(a){if(isPrecise(a.value*this.value)){return new SmallInteger(a.value*this.value)}return multiplySmallAndArray(Math.abs(a.value),smallToArray(Math.abs(this.value)),this.sign!==a.sign)};BigInteger.prototype._multiplyBySmall=function(a){if(a.value===0)return Integer[0];if(a.value===1)return this;if(a.value===-1)return this.negate();return multiplySmallAndArray(Math.abs(a.value),this.value,this.sign!==a.sign)};SmallInteger.prototype.multiply=function(v){return parseValue(v)._multiplyBySmall(this)};SmallInteger.prototype.times=SmallInteger.prototype.multiply;NativeBigInt.prototype.multiply=function(v){return new NativeBigInt(this.value*parseValue(v).value)};NativeBigInt.prototype.times=NativeBigInt.prototype.multiply;function square(a){var l=a.length,r=createArray(l+l),base=BASE,product,carry,i,a_i,a_j;for(i=0;i<l;i++){a_i=a[i];carry=0-a_i*a_i;for(var j=i;j<l;j++){a_j=a[j];product=2*(a_i*a_j)+r[i+j]+carry;carry=Math.floor(product/base);r[i+j]=product-carry*base}r[i+l]=carry}trim(r);return r}BigInteger.prototype.square=function(){return new BigInteger(square(this.value),false)};SmallInteger.prototype.square=function(){var value=this.value*this.value;if(isPrecise(value))return new SmallInteger(value);return new BigInteger(square(smallToArray(Math.abs(this.value))),false)};NativeBigInt.prototype.square=function(v){return new NativeBigInt(this.value*this.value)};function divMod1(a,b){var a_l=a.length,b_l=b.length,base=BASE,result=createArray(b.length),divisorMostSignificantDigit=b[b_l-1],lambda=Math.ceil(base/(2*divisorMostSignificantDigit)),remainder=multiplySmall(a,lambda),divisor=multiplySmall(b,lambda),quotientDigit,shift,carry,borrow,i,l,q;if(remainder.length<=a_l)remainder.push(0);divisor.push(0);divisorMostSignificantDigit=divisor[b_l-1];for(shift=a_l-b_l;shift>=0;shift--){quotientDigit=base-1;if(remainder[shift+b_l]!==divisorMostSignificantDigit){quotientDigit=Math.floor((remainder[shift+b_l]*base+remainder[shift+b_l-1])/divisorMostSignificantDigit)}carry=0;borrow=0;l=divisor.length;for(i=0;i<l;i++){carry+=quotientDigit*divisor[i];q=Math.floor(carry/base);borrow+=remainder[shift+i]-(carry-q*base);carry=q;if(borrow<0){remainder[shift+i]=borrow+base;borrow=-1}else{remainder[shift+i]=borrow;borrow=0}}while(borrow!==0){quotientDigit-=1;carry=0;for(i=0;i<l;i++){carry+=remainder[shift+i]-base+divisor[i];if(carry<0){remainder[shift+i]=carry+base;carry=0}else{remainder[shift+i]=carry;carry=1}}borrow+=carry}result[shift]=quotientDigit}remainder=divModSmall(remainder,lambda)[0];return[arrayToSmall(result),arrayToSmall(remainder)]}function divMod2(a,b){var a_l=a.length,b_l=b.length,result=[],part=[],base=BASE,guess,xlen,highx,highy,check;while(a_l){part.unshift(a[--a_l]);trim(part);if(compareAbs(part,b)<0){result.push(0);continue}xlen=part.length;highx=part[xlen-1]*base+part[xlen-2];highy=b[b_l-1]*base+b[b_l-2];if(xlen>b_l){highx=(highx+1)*base}guess=Math.ceil(highx/highy);do{check=multiplySmall(b,guess);if(compareAbs(check,part)<=0)break;guess--}while(guess);result.push(guess);part=subtract(part,check)}result.reverse();return[arrayToSmall(result),arrayToSmall(part)]}function divModSmall(value,lambda){var length=value.length,quotient=createArray(length),base=BASE,i,q,remainder,divisor;remainder=0;for(i=length-1;i>=0;--i){divisor=remainder*base+value[i];q=truncate(divisor/lambda);remainder=divisor-q*lambda;quotient[i]=q|0}return[quotient,remainder|0]}function divModAny(self,v){var value,n=parseValue(v);if(supportsNativeBigInt){return[new NativeBigInt(self.value/n.value),new NativeBigInt(self.value%n.value)]}var a=self.value,b=n.value;var quotient;if(b===0)throw new Error("Cannot divide by zero");if(self.isSmall){if(n.isSmall){return[new SmallInteger(truncate(a/b)),new SmallInteger(a%b)]}return[Integer[0],self]}if(n.isSmall){if(b===1)return[self,Integer[0]];if(b==-1)return[self.negate(),Integer[0]];var abs=Math.abs(b);if(abs<BASE){value=divModSmall(a,abs);quotient=arrayToSmall(value[0]);var remainder=value[1];if(self.sign)remainder=-remainder;if(typeof quotient==="number"){if(self.sign!==n.sign)quotient=-quotient;return[new SmallInteger(quotient),new SmallInteger(remainder)]}return[new BigInteger(quotient,self.sign!==n.sign),new SmallInteger(remainder)]}b=smallToArray(abs)}var comparison=compareAbs(a,b);if(comparison===-1)return[Integer[0],self];if(comparison===0)return[Integer[self.sign===n.sign?1:-1],Integer[0]];if(a.length+b.length<=200)value=divMod1(a,b);else value=divMod2(a,b);quotient=value[0];var qSign=self.sign!==n.sign,mod=value[1],mSign=self.sign;if(typeof quotient==="number"){if(qSign)quotient=-quotient;quotient=new SmallInteger(quotient)}else quotient=new BigInteger(quotient,qSign);if(typeof mod==="number"){if(mSign)mod=-mod;mod=new SmallInteger(mod)}else mod=new BigInteger(mod,mSign);return[quotient,mod]}BigInteger.prototype.divmod=function(v){var result=divModAny(this,v);return{quotient:result[0],remainder:result[1]}};NativeBigInt.prototype.divmod=SmallInteger.prototype.divmod=BigInteger.prototype.divmod;BigInteger.prototype.divide=function(v){return divModAny(this,v)[0]};NativeBigInt.prototype.over=NativeBigInt.prototype.divide=function(v){return new NativeBigInt(this.value/parseValue(v).value)};SmallInteger.prototype.over=SmallInteger.prototype.divide=BigInteger.prototype.over=BigInteger.prototype.divide;BigInteger.prototype.mod=function(v){return divModAny(this,v)[1]};NativeBigInt.prototype.mod=NativeBigInt.prototype.remainder=function(v){return new NativeBigInt(this.value%parseValue(v).value)};SmallInteger.prototype.remainder=SmallInteger.prototype.mod=BigInteger.prototype.remainder=BigInteger.prototype.mod;BigInteger.prototype.pow=function(v){var n=parseValue(v),a=this.value,b=n.value,value,x,y;if(b===0)return Integer[1];if(a===0)return Integer[0];if(a===1)return Integer[1];if(a===-1)return n.isEven()?Integer[1]:Integer[-1];if(n.sign){return Integer[0]}if(!n.isSmall)throw new Error("The exponent "+n.toString()+" is too large.");if(this.isSmall){if(isPrecise(value=Math.pow(a,b)))return new SmallInteger(truncate(value))}x=this;y=Integer[1];while(true){if(b&1===1){y=y.times(x);--b}if(b===0)break;b/=2;x=x.square()}return y};SmallInteger.prototype.pow=BigInteger.prototype.pow;NativeBigInt.prototype.pow=function(v){var n=parseValue(v);var a=this.value,b=n.value;var _0=BigInt(0),_1=BigInt(1),_2=BigInt(2);if(b===_0)return Integer[1];if(a===_0)return Integer[0];if(a===_1)return Integer[1];if(a===BigInt(-1))return n.isEven()?Integer[1]:Integer[-1];if(n.isNegative())return new NativeBigInt(_0);var x=this;var y=Integer[1];while(true){if((b&_1)===_1){y=y.times(x);--b}if(b===_0)break;b/=_2;x=x.square()}return y};BigInteger.prototype.modPow=function(exp,mod){exp=parseValue(exp);mod=parseValue(mod);if(mod.isZero())throw new Error("Cannot take modPow with modulus 0");var r=Integer[1],base=this.mod(mod);while(exp.isPositive()){if(base.isZero())return Integer[0];if(exp.isOdd())r=r.multiply(base).mod(mod);exp=exp.divide(2);base=base.square().mod(mod)}return r};NativeBigInt.prototype.modPow=SmallInteger.prototype.modPow=BigInteger.prototype.modPow;function compareAbs(a,b){if(a.length!==b.length){return a.length>b.length?1:-1}for(var i=a.length-1;i>=0;i--){if(a[i]!==b[i])return a[i]>b[i]?1:-1}return 0}BigInteger.prototype.compareAbs=function(v){var n=parseValue(v),a=this.value,b=n.value;if(n.isSmall)return 1;return compareAbs(a,b)};SmallInteger.prototype.compareAbs=function(v){var n=parseValue(v),a=Math.abs(this.value),b=n.value;if(n.isSmall){b=Math.abs(b);return a===b?0:a>b?1:-1}return-1};NativeBigInt.prototype.compareAbs=function(v){var a=this.value;var b=parseValue(v).value;a=a>=0?a:-a;b=b>=0?b:-b;return a===b?0:a>b?1:-1};BigInteger.prototype.compare=function(v){if(v===Infinity){return-1}if(v===-Infinity){return 1}var n=parseValue(v),a=this.value,b=n.value;if(this.sign!==n.sign){return n.sign?1:-1}if(n.isSmall){return this.sign?-1:1}return compareAbs(a,b)*(this.sign?-1:1)};BigInteger.prototype.compareTo=BigInteger.prototype.compare;SmallInteger.prototype.compare=function(v){if(v===Infinity){return-1}if(v===-Infinity){return 1}var n=parseValue(v),a=this.value,b=n.value;if(n.isSmall){return a==b?0:a>b?1:-1}if(a<0!==n.sign){return a<0?-1:1}return a<0?1:-1};SmallInteger.prototype.compareTo=SmallInteger.prototype.compare;NativeBigInt.prototype.compare=function(v){if(v===Infinity){return-1}if(v===-Infinity){return 1}var a=this.value;var b=parseValue(v).value;return a===b?0:a>b?1:-1};NativeBigInt.prototype.compareTo=NativeBigInt.prototype.compare;BigInteger.prototype.equals=function(v){return this.compare(v)===0};NativeBigInt.prototype.eq=NativeBigInt.prototype.equals=SmallInteger.prototype.eq=SmallInteger.prototype.equals=BigInteger.prototype.eq=BigInteger.prototype.equals;BigInteger.prototype.notEquals=function(v){return this.compare(v)!==0};NativeBigInt.prototype.neq=NativeBigInt.prototype.notEquals=SmallInteger.prototype.neq=SmallInteger.prototype.notEquals=BigInteger.prototype.neq=BigInteger.prototype.notEquals;BigInteger.prototype.greater=function(v){return this.compare(v)>0};NativeBigInt.prototype.gt=NativeBigInt.prototype.greater=SmallInteger.prototype.gt=SmallInteger.prototype.greater=BigInteger.prototype.gt=BigInteger.prototype.greater;BigInteger.prototype.lesser=function(v){return this.compare(v)<0};NativeBigInt.prototype.lt=NativeBigInt.prototype.lesser=SmallInteger.prototype.lt=SmallInteger.prototype.lesser=BigInteger.prototype.lt=BigInteger.prototype.lesser;BigInteger.prototype.greaterOrEquals=function(v){return this.compare(v)>=0};NativeBigInt.prototype.geq=NativeBigInt.prototype.greaterOrEquals=SmallInteger.prototype.geq=SmallInteger.prototype.greaterOrEquals=BigInteger.prototype.geq=BigInteger.prototype.greaterOrEquals;BigInteger.prototype.lesserOrEquals=function(v){return this.compare(v)<=0};NativeBigInt.prototype.leq=NativeBigInt.prototype.lesserOrEquals=SmallInteger.prototype.leq=SmallInteger.prototype.lesserOrEquals=BigInteger.prototype.leq=BigInteger.prototype.lesserOrEquals;BigInteger.prototype.isEven=function(){return(this.value[0]&1)===0};SmallInteger.prototype.isEven=function(){return(this.value&1)===0};NativeBigInt.prototype.isEven=function(){return(this.value&BigInt(1))===BigInt(0)};BigInteger.prototype.isOdd=function(){return(this.value[0]&1)===1};SmallInteger.prototype.isOdd=function(){return(this.value&1)===1};NativeBigInt.prototype.isOdd=function(){return(this.value&BigInt(1))===BigInt(1)};BigInteger.prototype.isPositive=function(){return!this.sign};SmallInteger.prototype.isPositive=function(){return this.value>0};NativeBigInt.prototype.isPositive=SmallInteger.prototype.isPositive;BigInteger.prototype.isNegative=function(){return this.sign};SmallInteger.prototype.isNegative=function(){return this.value<0};NativeBigInt.prototype.isNegative=SmallInteger.prototype.isNegative;BigInteger.prototype.isUnit=function(){return false};SmallInteger.prototype.isUnit=function(){return Math.abs(this.value)===1};NativeBigInt.prototype.isUnit=function(){return this.abs().value===BigInt(1)};BigInteger.prototype.isZero=function(){return false};SmallInteger.prototype.isZero=function(){return this.value===0};NativeBigInt.prototype.isZero=function(){return this.value===BigInt(0)};BigInteger.prototype.isDivisibleBy=function(v){var n=parseValue(v);if(n.isZero())return false;if(n.isUnit())return true;if(n.compareAbs(2)===0)return this.isEven();return this.mod(n).isZero()};NativeBigInt.prototype.isDivisibleBy=SmallInteger.prototype.isDivisibleBy=BigInteger.prototype.isDivisibleBy;function isBasicPrime(v){var n=v.abs();if(n.isUnit())return false;if(n.equals(2)||n.equals(3)||n.equals(5))return true;if(n.isEven()||n.isDivisibleBy(3)||n.isDivisibleBy(5))return false;if(n.lesser(49))return true}function millerRabinTest(n,a){var nPrev=n.prev(),b=nPrev,r=0,d,t,i,x;while(b.isEven())b=b.divide(2),r++;next:for(i=0;i<a.length;i++){if(n.lesser(a[i]))continue;x=bigInt(a[i]).modPow(b,n);if(x.isUnit()||x.equals(nPrev))continue;for(d=r-1;d!=0;d--){x=x.square().mod(n);if(x.isUnit())return false;if(x.equals(nPrev))continue next}return false}return true}BigInteger.prototype.isPrime=function(strict){var isPrime=isBasicPrime(this);if(isPrime!==undefined)return isPrime;var n=this.abs();var bits=n.bitLength();if(bits<=64)return millerRabinTest(n,[2,3,5,7,11,13,17,19,23,29,31,37]);var logN=Math.log(2)*bits.toJSNumber();var t=Math.ceil(strict===true?2*Math.pow(logN,2):logN);for(var a=[],i=0;i<t;i++){a.push(bigInt(i+2))}return millerRabinTest(n,a)};NativeBigInt.prototype.isPrime=SmallInteger.prototype.isPrime=BigInteger.prototype.isPrime;BigInteger.prototype.isProbablePrime=function(iterations){var isPrime=isBasicPrime(this);if(isPrime!==undefined)return isPrime;var n=this.abs();var t=iterations===undefined?5:iterations;for(var a=[],i=0;i<t;i++){a.push(bigInt.randBetween(2,n.minus(2)))}return millerRabinTest(n,a)};NativeBigInt.prototype.isProbablePrime=SmallInteger.prototype.isProbablePrime=BigInteger.prototype.isProbablePrime;BigInteger.prototype.modInv=function(n){var t=bigInt.zero,newT=bigInt.one,r=parseValue(n),newR=this.abs(),q,lastT,lastR;while(!newR.isZero()){q=r.divide(newR);lastT=t;lastR=r;t=newT;r=newR;newT=lastT.subtract(q.multiply(newT));newR=lastR.subtract(q.multiply(newR))}if(!r.isUnit())throw new Error(this.toString()+" and "+n.toString()+" are not co-prime");if(t.compare(0)===-1){t=t.add(n)}if(this.isNegative()){return t.negate()}return t};NativeBigInt.prototype.modInv=SmallInteger.prototype.modInv=BigInteger.prototype.modInv;BigInteger.prototype.next=function(){var value=this.value;if(this.sign){return subtractSmall(value,1,this.sign)}return new BigInteger(addSmall(value,1),this.sign)};SmallInteger.prototype.next=function(){var value=this.value;if(value+1<MAX_INT)return new SmallInteger(value+1);return new BigInteger(MAX_INT_ARR,false)};NativeBigInt.prototype.next=function(){return new NativeBigInt(this.value+BigInt(1))};BigInteger.prototype.prev=function(){var value=this.value;if(this.sign){return new BigInteger(addSmall(value,1),true)}return subtractSmall(value,1,this.sign)};SmallInteger.prototype.prev=function(){var value=this.value;if(value-1>-MAX_INT)return new SmallInteger(value-1);return new BigInteger(MAX_INT_ARR,true)};NativeBigInt.prototype.prev=function(){return new NativeBigInt(this.value-BigInt(1))};var powersOfTwo=[1];while(2*powersOfTwo[powersOfTwo.length-1]<=BASE)powersOfTwo.push(2*powersOfTwo[powersOfTwo.length-1]);var powers2Length=powersOfTwo.length,highestPower2=powersOfTwo[powers2Length-1];function shift_isSmall(n){return Math.abs(n)<=BASE}BigInteger.prototype.shiftLeft=function(v){var n=parseValue(v).toJSNumber();if(!shift_isSmall(n)){throw new Error(String(n)+" is too large for shifting.")}if(n<0)return this.shiftRight(-n);var result=this;if(result.isZero())return result;while(n>=powers2Length){result=result.multiply(highestPower2);n-=powers2Length-1}return result.multiply(powersOfTwo[n])};NativeBigInt.prototype.shiftLeft=SmallInteger.prototype.shiftLeft=BigInteger.prototype.shiftLeft;BigInteger.prototype.shiftRight=function(v){var remQuo;var n=parseValue(v).toJSNumber();if(!shift_isSmall(n)){throw new Error(String(n)+" is too large for shifting.")}if(n<0)return this.shiftLeft(-n);var result=this;while(n>=powers2Length){if(result.isZero()||result.isNegative()&&result.isUnit())return result;remQuo=divModAny(result,highestPower2);result=remQuo[1].isNegative()?remQuo[0].prev():remQuo[0];n-=powers2Length-1}remQuo=divModAny(result,powersOfTwo[n]);return remQuo[1].isNegative()?remQuo[0].prev():remQuo[0]};NativeBigInt.prototype.shiftRight=SmallInteger.prototype.shiftRight=BigInteger.prototype.shiftRight;function bitwise(x,y,fn){y=parseValue(y);var xSign=x.isNegative(),ySign=y.isNegative();var xRem=xSign?x.not():x,yRem=ySign?y.not():y;var xDigit=0,yDigit=0;var xDivMod=null,yDivMod=null;var result=[];while(!xRem.isZero()||!yRem.isZero()){xDivMod=divModAny(xRem,highestPower2);xDigit=xDivMod[1].toJSNumber();if(xSign){xDigit=highestPower2-1-xDigit}yDivMod=divModAny(yRem,highestPower2);yDigit=yDivMod[1].toJSNumber();if(ySign){yDigit=highestPower2-1-yDigit}xRem=xDivMod[0];yRem=yDivMod[0];result.push(fn(xDigit,yDigit))}var sum=fn(xSign?1:0,ySign?1:0)!==0?bigInt(-1):bigInt(0);for(var i=result.length-1;i>=0;i-=1){sum=sum.multiply(highestPower2).add(bigInt(result[i]))}return sum}BigInteger.prototype.not=function(){return this.negate().prev()};NativeBigInt.prototype.not=SmallInteger.prototype.not=BigInteger.prototype.not;BigInteger.prototype.and=function(n){return bitwise(this,n,function(a,b){return a&b})};NativeBigInt.prototype.and=SmallInteger.prototype.and=BigInteger.prototype.and;BigInteger.prototype.or=function(n){return bitwise(this,n,function(a,b){return a|b})};NativeBigInt.prototype.or=SmallInteger.prototype.or=BigInteger.prototype.or;BigInteger.prototype.xor=function(n){return bitwise(this,n,function(a,b){return a^b})};NativeBigInt.prototype.xor=SmallInteger.prototype.xor=BigInteger.prototype.xor;var LOBMASK_I=1<<30,LOBMASK_BI=(BASE&-BASE)*(BASE&-BASE)|LOBMASK_I;function roughLOB(n){var v=n.value,x=typeof v==="number"?v|LOBMASK_I:typeof v==="bigint"?v|BigInt(LOBMASK_I):v[0]+v[1]*BASE|LOBMASK_BI;return x&-x}function integerLogarithm(value,base){if(base.compareTo(value)<=0){var tmp=integerLogarithm(value,base.square(base));var p=tmp.p;var e=tmp.e;var t=p.multiply(base);return t.compareTo(value)<=0?{p:t,e:e*2+1}:{p:p,e:e*2}}return{p:bigInt(1),e:0}}BigInteger.prototype.bitLength=function(){var n=this;if(n.compareTo(bigInt(0))<0){n=n.negate().subtract(bigInt(1))}if(n.compareTo(bigInt(0))===0){return bigInt(0)}return bigInt(integerLogarithm(n,bigInt(2)).e).add(bigInt(1))};NativeBigInt.prototype.bitLength=SmallInteger.prototype.bitLength=BigInteger.prototype.bitLength;function max(a,b){a=parseValue(a);b=parseValue(b);return a.greater(b)?a:b}function min(a,b){a=parseValue(a);b=parseValue(b);return a.lesser(b)?a:b}function gcd(a,b){a=parseValue(a).abs();b=parseValue(b).abs();if(a.equals(b))return a;if(a.isZero())return b;if(b.isZero())return a;var c=Integer[1],d,t;while(a.isEven()&&b.isEven()){d=min(roughLOB(a),roughLOB(b));a=a.divide(d);b=b.divide(d);c=c.multiply(d)}while(a.isEven()){a=a.divide(roughLOB(a))}do{while(b.isEven()){b=b.divide(roughLOB(b))}if(a.greater(b)){t=b;b=a;a=t}b=b.subtract(a)}while(!b.isZero());return c.isUnit()?a:a.multiply(c)}function lcm(a,b){a=parseValue(a).abs();b=parseValue(b).abs();return a.divide(gcd(a,b)).multiply(b)}function randBetween(a,b){a=parseValue(a);b=parseValue(b);var low=min(a,b),high=max(a,b);var range=high.subtract(low).add(1);if(range.isSmall)return low.add(Math.floor(Math.random()*range));var digits=toBase(range,BASE).value;var result=[],restricted=true;for(var i=0;i<digits.length;i++){var top=restricted?digits[i]:BASE;var digit=truncate(Math.random()*top);result.push(digit);if(digit<top)restricted=false}return low.add(Integer.fromArray(result,BASE,false))}var parseBase=function(text,base,alphabet,caseSensitive){alphabet=alphabet||DEFAULT_ALPHABET;text=String(text);if(!caseSensitive){text=text.toLowerCase();alphabet=alphabet.toLowerCase()}var length=text.length;var i;var absBase=Math.abs(base);var alphabetValues={};for(i=0;i<alphabet.length;i++){alphabetValues[alphabet[i]]=i}for(i=0;i<length;i++){var c=text[i];if(c==="-")continue;if(c in alphabetValues){if(alphabetValues[c]>=absBase){if(c==="1"&&absBase===1)continue;throw new Error(c+" is not a valid digit in base "+base+".")}}}base=parseValue(base);var digits=[];var isNegative=text[0]==="-";for(i=isNegative?1:0;i<text.length;i++){var c=text[i];if(c in alphabetValues)digits.push(parseValue(alphabetValues[c]));else if(c==="<"){var start=i;do{i++}while(text[i]!==">"&&i<text.length);digits.push(parseValue(text.slice(start+1,i)))}else throw new Error(c+" is not a valid character")}return parseBaseFromArray(digits,base,isNegative)};function parseBaseFromArray(digits,base,isNegative){var val=Integer[0],pow=Integer[1],i;for(i=digits.length-1;i>=0;i--){val=val.add(digits[i].times(pow));pow=pow.times(base)}return isNegative?val.negate():val}function stringify(digit,alphabet){alphabet=alphabet||DEFAULT_ALPHABET;if(digit<alphabet.length){return alphabet[digit]}return"<"+digit+">"}function toBase(n,base){base=bigInt(base);if(base.isZero()){if(n.isZero())return{value:[0],isNegative:false};throw new Error("Cannot convert nonzero numbers to base 0.")}if(base.equals(-1)){if(n.isZero())return{value:[0],isNegative:false};if(n.isNegative())return{value:[].concat.apply([],Array.apply(null,Array(-n.toJSNumber())).map(Array.prototype.valueOf,[1,0])),isNegative:false};var arr=Array.apply(null,Array(n.toJSNumber()-1)).map(Array.prototype.valueOf,[0,1]);arr.unshift([1]);return{value:[].concat.apply([],arr),isNegative:false}}var neg=false;if(n.isNegative()&&base.isPositive()){neg=true;n=n.abs()}if(base.isUnit()){if(n.isZero())return{value:[0],isNegative:false};return{value:Array.apply(null,Array(n.toJSNumber())).map(Number.prototype.valueOf,1),isNegative:neg}}var out=[];var left=n,divmod;while(left.isNegative()||left.compareAbs(base)>=0){divmod=left.divmod(base);left=divmod.quotient;var digit=divmod.remainder;if(digit.isNegative()){digit=base.minus(digit).abs();left=left.next()}out.push(digit.toJSNumber())}out.push(left.toJSNumber());return{value:out.reverse(),isNegative:neg}}function toBaseString(n,base,alphabet){var arr=toBase(n,base);return(arr.isNegative?"-":"")+arr.value.map(function(x){return stringify(x,alphabet)}).join("")}BigInteger.prototype.toArray=function(radix){return toBase(this,radix)};SmallInteger.prototype.toArray=function(radix){return toBase(this,radix)};NativeBigInt.prototype.toArray=function(radix){return toBase(this,radix)};BigInteger.prototype.toString=function(radix,alphabet){if(radix===undefined)radix=10;if(radix!==10)return toBaseString(this,radix,alphabet);var v=this.value,l=v.length,str=String(v[--l]),zeros="0000000",digit;while(--l>=0){digit=String(v[l]);str+=zeros.slice(digit.length)+digit}var sign=this.sign?"-":"";return sign+str};SmallInteger.prototype.toString=function(radix,alphabet){if(radix===undefined)radix=10;if(radix!=10)return toBaseString(this,radix,alphabet);return String(this.value)};NativeBigInt.prototype.toString=SmallInteger.prototype.toString;NativeBigInt.prototype.toJSON=BigInteger.prototype.toJSON=SmallInteger.prototype.toJSON=function(){return this.toString()};BigInteger.prototype.valueOf=function(){return parseInt(this.toString(),10)};BigInteger.prototype.toJSNumber=BigInteger.prototype.valueOf;SmallInteger.prototype.valueOf=function(){return this.value};SmallInteger.prototype.toJSNumber=SmallInteger.prototype.valueOf;NativeBigInt.prototype.valueOf=NativeBigInt.prototype.toJSNumber=function(){return parseInt(this.toString(),10)};function parseStringValue(v){if(isPrecise(+v)){var x=+v;if(x===truncate(x))return supportsNativeBigInt?new NativeBigInt(BigInt(x)):new SmallInteger(x);throw new Error("Invalid integer: "+v)}var sign=v[0]==="-";if(sign)v=v.slice(1);var split=v.split(/e/i);if(split.length>2)throw new Error("Invalid integer: "+split.join("e"));if(split.length===2){var exp=split[1];if(exp[0]==="+")exp=exp.slice(1);exp=+exp;if(exp!==truncate(exp)||!isPrecise(exp))throw new Error("Invalid integer: "+exp+" is not a valid exponent.");var text=split[0];var decimalPlace=text.indexOf(".");if(decimalPlace>=0){exp-=text.length-decimalPlace-1;text=text.slice(0,decimalPlace)+text.slice(decimalPlace+1)}if(exp<0)throw new Error("Cannot include negative exponent part for integers");text+=new Array(exp+1).join("0");v=text}var isValid=/^([0-9][0-9]*)$/.test(v);if(!isValid)throw new Error("Invalid integer: "+v);if(supportsNativeBigInt){return new NativeBigInt(BigInt(sign?"-"+v:v))}var r=[],max=v.length,l=LOG_BASE,min=max-l;while(max>0){r.push(+v.slice(min,max));min-=l;if(min<0)min=0;max-=l}trim(r);return new BigInteger(r,sign)}function parseNumberValue(v){if(supportsNativeBigInt){return new NativeBigInt(BigInt(v))}if(isPrecise(v)){if(v!==truncate(v))throw new Error(v+" is not an integer.");return new SmallInteger(v)}return parseStringValue(v.toString())}function parseValue(v){if(typeof v==="number"){return parseNumberValue(v)}if(typeof v==="string"){return parseStringValue(v)}if(typeof v==="bigint"){return new NativeBigInt(v)}return v}for(var i=0;i<1e3;i++){Integer[i]=parseValue(i);if(i>0)Integer[-i]=parseValue(-i)}Integer.one=Integer[1];Integer.zero=Integer[0];Integer.minusOne=Integer[-1];Integer.max=max;Integer.min=min;Integer.gcd=gcd;Integer.lcm=lcm;Integer.isInstance=function(x){return x instanceof BigInteger||x instanceof SmallInteger||x instanceof NativeBigInt};Integer.randBetween=randBetween;Integer.fromArray=function(digits,base,isNegative){return parseBaseFromArray(digits.map(parseValue),parseValue(base||10),isNegative)};return Integer}();if(typeof module!=="undefined"&&module.hasOwnProperty("exports")){module.exports=bigInt}if(typeof define==="function"&&define.amd){define("big-integer",[],function(){return bigInt})}

/**
 * @param input string[]
 */
function Main(input) {
  const n = bigInt(input[0]);
  const a = bigInt(input[1]);
  const b = bigInt(input[2]);

  var answer;
  const diff = b.minus(a);
  if (diff.mod(2).isZero()) {
    answer = diff.mod(2);
  } else {
    // 端との距離が近い方で調整
    var roundsForFix;
    // aが1に近い場合
    if (a.minus(1).compare(n.minus(b)) < 0) {
      // aが卓1で勝利するまでの試合数
      roundsForFix = a;
      const bFixed = b.minus(roundsForFix);
      // a = 1
      answer = roundsForFix.plus(bFixed.minus(1).divide(2));
    // bがNに近い場合
    } else {
      // bが卓Nで敗亡するまでの試合数
      roundsForFix = n.minus(b).plus(1);
      const aFixed = a.plus(roundsForFix);
      // b = n
      answer = roundsForFix.plus(n.minus(aFixed).divide(2));
    }
  }

  console.log(answer.toString());
}

Main(require("fs").readFileSync("/dev/stdin", "utf8").trim().split(" "));