bzoj 1876

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int maxn = 10010;
const int inf = 1000000000;

struct bgint {
    int n, a[maxn]; 
    bgint() {
        n = 0; memset(a, 0, sizeof(a));
    }
    bgint operator - (const bgint &x) const {
        bgint ret; ret.n = max(x. n, this-> n); 
        for(int i = 1; i <= ret. n; ++ i) {
            ret. a[i] += this-> a[i] - x. a[i];
            if(ret. a[i] < 0) ret. a[i] += inf, ret. a[i + 1] --;
        }
        while(ret. a[ret. n] == 0 && ret. n != 1) ret. n --; 
        return ret;
    }
};

bgint mov(const bgint &x) {
    bgint ret; ret. n = x. n;
    for(int i = 1; i <= ret. n; ++ i) {
        ret. a[i] += x. a[i] * 2; 
        ret. a[i + 1] += ret. a[i] / inf;
        ret. a[i] %= inf;
    }
    if(ret. a[ret. n + 1]) ret. n ++;
    return ret;
}

bgint div(const bgint &x) {
    bgint ret; 
    if(x. a[x.n] < 2) {
        ret. n = x. n - 1;
        for(int i = 1; i <= ret. n; ++ i) ret. a[i] = x. a[i]; 
        ret. a[ret. n] += x. a[x.n] * inf; 
        for(int i = ret. n; i >= 1; -- i) ret. a[i - 1] += ret. a[i] % 2 * inf, ret. a[i] /= 2; 
        ret. a[0] = 0;
    }
    else {
        ret. n = x.n;
        for(int i = 1; i <= ret. n; ++ i) ret. a[i] = x. a[i]; 
        for(int i = ret. n; i >= 1; -- i) ret. a[i - 1] += ret. a[i] % 2 * inf, ret. a[i] /= 2; 
        ret. a[0] = 0;
    }
    return ret;
}
 
bool even (const bgint &x) { 
    return (x. a[1] & 1);
}

bool is (const bgint &x, const bgint &t) {
    if(x. n != t. n) return 0;
    for(int i = 1; i <= x. n; ++ i) if(x. a[i] != t. a[i]) return 0;
    return 1;
}

bool com(const bgint &x, const bgint &t) {
    if(x. n > t. n) return 0;
    else if(x. n < t. n) return 1;
    for(int i = x. n; i >= 1; -- i) {
        if(x. a[i] > t. a[i]) return 0;
        else if(x. a[i] < t.a[i]) return 1;
    }
    return 0;
}

void print(const bgint &x) {
    for(int i = x. n; i >= 1; -- i) {
        if(i == x.n ) printf("%d", x. a[i]);
        else printf("%09d", x. a[i]);
    }
}

bgint gcd(bgint a, bgint b) {
    bgint ret; ret. a[1] = 1, ret. n = 1; 
    int cnt = 0;
    while(!is(a, b)) {
        if(even(a)) {
            if(even(b)) {
                if(!com(a, b)) a = div((a - b));
                else b = div((b - a)); 
            }
            else b = div(b); 
        }
        else {
            if(even(b)) a = div(a);
            else b = div(b), a = div(a), cnt ++;
        }
       // ++ x; print(a); cout << " "; print(b); cout << endl;
    }
    for(int i = 1; i <= cnt; ++ i) a = mov(a);
    return a;
}

char s[maxn]; 

bgint read() {
    scanf("%s", s + 1);
    bgint ret; ret. n = (int)strlen(s + 1); ret. n = ret. n % 9 == 0 ? ret. n / 9 : ret. n / 9 + 1;
    int sl = (int)strlen(s + 1);
    for(int i = 1; i <= ret. n; ++ i) {
        int t = 1;
        for(int j = (i - 1) * 9 + 1; j <= min(i * 9, sl); ++ j) 
            ret. a[i] += (int)(s[sl - j + 1] - ‘0‘) * t, t *= 10; 
    }
    return ret;
}

void sov() {
    bgint x = read(), t = read();  
    print(gcd(x, t));
}

int main() {
    //freopen("test.in", "r", stdin);
    //freopen("test.out", "w", stdout);
    sov();
    return 0;
}