#include <stdio.h>
#include <assert.h>

int BitCheck(int total,int n,int last) {
    FILE *input,*output0,*output1;
    char filename[10] = "";
    int mask,value,num0 = 0,num1 = 0;
    assert(n>=0);
    if(n==total)
        input = fopen("output.txt","r");
    else {
        sprintf(filename,
 
"%d_%d.txt",n,last);
        input = fopen(filename,"r");
    }
    if(n==0) {
        sprintf(filename,"final_0");
        output0 = fopen(filename,"w");
        sprintf(filename,"final_1");
        output1 = fopen(filename,"w");
    }
    else {
        sprintf(filename,"%d_0.txt",n-1);
        output0 
 
= fopen(filename,"w");
        sprintf(filename,"%d_1.txt",n-1);
        output1 = fopen(filename,"w");
    }
    assert(input!=NULL && output0!=NULL&&output1!=NULL);
    mask = 1<<n;
    while(!feof(input)) {
        fscanf(input,"%d\n",&value);
        if(value&mask) {
            fprintf(output1,
 
"%d\n",value);
            num1++;
        }
        else {
            fprintf(output0,"%d\n",value);
            num0++;
        }
    }
    fflush(output0);
    fflush(output1);
    fclose(output0);
    fclose(output1);
    fclose(input);
    return num1<num0;
}

int Search(int n){
    int total = n,last = 0,missing =0;
    while(n>=0) {
        last = BitCheck(total,n,last);
        missing |= (last<<n);
        n--;
    }
    printf("missing number:%d\n",missing);
    return 0;
}


int main() {
    Search(14);
    return 0;
}