documents.c

#include <stdio.h>
FILE *fout;
FILE* fin;
#define N_MAX 10000000
int A[N_MAX];
void exchange(int space);

int main(){
    fin = fopen("input.txt","r");
    fout = fopen("output.txt", "w");
    int N;
    fscanf(fin, "%d\n", &N);
    int K = 0;
    for (int i = 1;i <= N;i++){
        fscanf(fin, "%d ",&A[i]);
        if (A[i] != i)
            K++;
        }
    fprintf(fout, "%d\n", K*2);
    for (int i = 1;i <= N;i++){
        exchange(i);
    }
    return 0;
}
void exchange(int i){
    int doc = A[i];
    int space = i;
    if (doc == space){
        return;
    }
    fprintf(fout, "-%d %d\n", A[i], i);
    while(doc != space){
        int right_doc = A[doc];
        fprintf(fout, "-%d %d\n", right_doc, doc);
        fprintf(fout, "%d %d\n", doc, doc);
        A[doc] = doc;
        doc = right_doc;
    }
    fprintf(fout, "%d %d\n", space, doc);
    A[space] = doc;
}