#include<iostream>

 #include<stdio.h>

 #include<string>

 #include<math.h>

 #define PI acos(-1)

 //using namespace std;

 struct Nod

 {

     int dir;

     int len;

 }node[];

 struct Point

 {

 double x;

 double y;

 };

 struct segmemt

 {

     Point s;

     Point t;

 };

 double MAX(double a,double b)

 {

 if(a>b)return a;

 return b;

 }

 double MIN(double a,double b)

 {

 if(a<b)return a;

 return b;

 }

 double mulpti(Point ps , Point pe , Point p)

 {

 return (pe.x-ps.x)*(p.y-ps.y)-(p.x-ps.x)*(pe.y-ps.y);

 }

 bool inser(Point p1, Point p2 , Point p3, Point p4)  //判断线段是否相交

 {

 if(MAX(p1.x,p2.x)>=MIN(p3.x,p4.x) &&

      MAX(p3.x,p4.x)>=MIN(p1.x,p2.x) &&

      MAX(p1.y,p2.y)>=MIN(p3.y,p4.y) &&

      MAX(p3.y,p4.y)>=MIN(p1.y,p2.y) &&

      mulpti(p1,p2,p3)*mulpti(p1,p2,p4)<= &&

      mulpti(p3,p4,p1)*mulpti(p3,p4,p2)<=)

      return true;  //相交

 else

      return false;  //不相交

 }

 //得到向量的x坐标

 double getX(double x,double y,int dir) //传入(x,y)向量以及角度dir

 {

     return x*cos(dir/180.0*PI)-y*sin(dir/180.0*PI);

 }

 //得到向量的y坐标

 double getY(double x,double y,int dir)

 {

     return y*cos(dir/180.0*PI)+x*sin(dir/180.0*PI);

 }

 int main()

 {

     int n;

     segmemt list[];

     while(~scanf("%d",&n)&&n)

     {

         int i;

         double x,y,tx,ty;

         for(i=;i<n;i++)

         {

             scanf("%d%d",&node[i].dir,&node[i].len);

             if(node[i].dir<)   node[i].dir=+node[i].dir;

         }

         list[].s.x=;

         list[].s.y=;

         x = getX(,,node[].dir);

         y = getY(,,node[].dir);

         list[].t.x = x*node[].len;

         list[].t.y = y*node[].len;

         for(i=;i<n;i++)

         {

             list[i].s.x = list[i-].t.x;

             list[i].s.y = list[i-].t.y;

             tx = x;

             ty = y;

             x = getX(tx,ty,node[i].dir);

             y = getY(tx,ty,node[i].dir);

             list[i].t.x = x*node[i].len + list[i].s.x;

             list[i].t.y = y*node[i].len + list[i].s.y;

         }

         int j,flag=;

         for(i=;i<n;i++)

         {

             for(j=;j<=i-;j++)

             {

                 if(inser(list[j].s,list[j].t,list[i].s,list[i].t))

                 {

                     flag = ;

                     printf("%d\n",i+);

                     break;

                 }

             }

             if(flag)    break;

         }

         if(!flag)

         {

             puts("SAFE");

         }

     }

     return ;

 }