#include <cstdio> #include <cmath> #include <cfloat> using namespace std; int main () { #ifdef CONTEST freopen("242b.in", "rt", stdin); freopen("242b.out", "wt", stdout); #endif int n; scanf("%d", &n); int a[n], b[n]; int min_a = 0, max_b = 0; int best_i; for(int i = 0; i < n; i++) { scanf("%d %d", &a[i], &b[i]); if(max_b - min_a <= b[i] - a[i]) { max_b = b[i]; min_a = a[i]; best_i = i + 1; } } for(int i = 0; i < n; i++) { if(a[i] < min_a || b[i] > max_b) { printf("-1\n"); return 0; } } printf("%d\n", best_i); return 0; }