/** *中国剩余定理 */ #include<iostream> #include<cstdio> #include<map> #include<cstring> #include<string> #include<algorithm> #include<queue> #include<vector> #include<stack> #include<cstdlib> #include<cctype> #include<cstring> #include<cmath> #define LL __int64 using namespace std; /** *gcd(a,b)=d;则存在x,y,使d=ax+by *extended_euclid(a,b)=ax+by */ LL extended_euclid(LL a,LL b,LL &x,LL &y){//扩张欧几里的算法 int d; if(b==0){ x=1; y=0; return a; } d=extended_euclid(b,a%b,y,x); y=y-a/b*x; return d; } /** *x=b[i](modw[i]) o<i<len *w[i]>0,且w[]中任意两个数互质 */ LL chinese_remainder(int b[],int w[],int len){ LL res,i,d,x,y,n,m; res=0; n=1; for(i=0;i<len;i++) n*=w[i]; for(i=0;i<len;i++){ m=n/w[i]; extended_euclid(w[i],m,x,y); res=(res+y*m*b[i])%n; } return (n+res%n)%n; } int main() { int len,b[12],w[12]; while(cin>>len){ for(int i=0;i<len;i++){ cin>>w[i]>>b[i]; } cout<<chinese_remainder(b,w,len)<<endl; } return 0; }