#include<stdio.h>#include<stdlib.h>using namespace std;typedef int ElementType;int ans;void Merge(ElementType A[], ElementType TmpArray[], int Lpos, int Rpos, int RightEnd){int i , LeftEnd, NumElements, TmpPos;LeftEnd = Rpos - 1;TmpPos = Lpos;NumElements = RightEnd - Lpos + 1;while(Lpos <= LeftEnd && Rpos <= RightEnd){if(A[Lpos] <= A[Rpos])TmpArray[TmpPos++] = A[Lpos++];else{ans += (LeftEnd - Lpos + 1); TmpArray[TmpPos++] = A[Rpos++];}}while(Lpos <= LeftEnd) {TmpArray[TmpPos++] = A[Lpos++];}while(Rpos <= RightEnd){TmpArray[TmpPos++] = A[Rpos++];}for(i = 0; i < NumElements; ++i, --RightEnd)A[RightEnd] = TmpArray[RightEnd];}void MSort(ElementType A[], ElementType TmpArray[], int Left, int Right){int Center = 0;if(Left < Right){Center = (Left + Right) >> 1;MSort(A, TmpArray, Left, Center);MSort(A, TmpArray, Center + 1, Right);Merge(A, TmpArray, Left, Center + 1, Right);}}void MergeSort(ElementType A[], int N){ElementType* TmpArray = NULL;TmpArray = (ElementType*) malloc(N * sizeof(ElementType));if(NULL != TmpArray){MSort(A, TmpArray, 0, N - 1);free(TmpArray);}elseprintf("allocate temp memory failn");}int Arr[1001];int mires[2][1001];int main(int argc, char* argv[]){int n;while(scanf("%d",&n)!=EOF){for(int i = 1; i <= n; ++i)scanf("%d %d", &mires[0][i], &mires[1][i]);for(int i = 1; i <= n; ++i) {for(int j = 1; j <= n; ++j) {if(mires[0][i] == mires[1][j]) {Arr[i-1] = j;break;}}}ans = 0;MergeSort(Arr,n);printf("%dn",ans);}}
