2020-10-18

#include<bits/stdc++.h>

#define vint vector<int>
#define vstr vector<string>
#define vll vector<long long>
#define ll long long
#define pf printf
#define sf scanf
#define sfd(n) scanf("%d", &n)
#define sflf(n) scanf("%lf", &n)
#define sfll(n) scanf("%lld", &n)
#define pfd(n) printf("%d", n)
#define pflf(n) printf("%lf", n)
#define pfll(n) printf("%lld", n)
#define pft	printf("\t")
#define pfn printf("\n")
#define pfk printf(" ")
#define PI 3.1415926
#define MAX 200020
#define M 1e18
#define F -1e6
#define E 1e6

using namespace std;
/*
ll gcd(int a, int b) {
	if( b==0 ) {
		return a;
	}
	return gcd(b, a%b);
}
*/
int main() {

	int n;
	cin >> n;
	ll a, b, c, d;
	if( n>0 ) {
		sf("%lld/%lld", &c, &d);
		for( int i=1; i<n; i++ ) {
	//		pf("%lld/%lld", c, d);
	//		pfn;

			sf("%lld/%lld", &a, &b);
			ll e = d/__gcd(b, d)*b;
			c = e/d*c+e/b*a;
			d = e;
		}
		int f = 1;
		if( c<0 ) {
			f = 0;
			c = -c;
		}
		ll e = __gcd(c, d);
		c = c/e;
		d = d/e;
		ll g = c/d;
		c = c%d;
		if( f==0 ) {
			g = -g;
			c = -c;
		}
		if( g ) {
			pfll(g);
		}
		if( c ) {
			if( g ) pfk;
			pf("%lld/%lld", c, d);
		}
		if( !g&&!c ) {
			pfd(0);
		}
	}else {
		pfd(0);
	}

	return 0;
}

PS：还是不懂自己的gcd比__gcd不行。