#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char*mmap();
#define rd_skip() while(*rp++>=48)
#define rd(v) int v=0;{int _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}
#define rd_long(v) long v=0;{int _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}

#define WTHI(v) {long _z=v,_n=0,_d=0;while(++_n,_d=_d<<8|0x30|_z%10,_z/=10);*(long*)wp=_d;wp+=_n;}
#define WTLO(v) {long _z=v,_n=8,_d=0;while(_d=_d<<8|0x30|_z%10,_z/=10,--_n);*(long*)wp=_d;wp+=8;}
#define wt(v) if(v>=100000000){WTHI(v/100000000);WTLO(v);}else{WTHI(v);}

#define rep(v,e) for(int v=0;v<e;++v)
#define chmin(v,a) (v=v<=a?v:a)

void radix_sort_aux(unsigned long*a,unsigned long*b,int n){
	int c[256];
	for(int i=0;i<256;++i){
		c[i]=0;
	}
	for(int i=0;i<n;++i){
		++c[a[i]&255];
	}
	int t=0;
	for(int i=0;i<256;++i){
		int u=c[i];
		c[i]=t;
		t+=u;
	}
	for(int i=0;i<n;++i){
		b[c[a[i]&255]++]=a[i]>>8|a[i]<<56;
	}
}

long rsbuf[1<<16];

void radix_sort(unsigned long*a,int n){
	radix_sort_aux(a,rsbuf,n);
	radix_sort_aux(rsbuf,a,n);
	radix_sort_aux(a,rsbuf,n);
	radix_sort_aux(rsbuf,a,n);
	radix_sort_aux(a,rsbuf,n);
	for(int i=0;i<n;++i){
		a[i]=rsbuf[i]>>24;
	}
}

long d1[1<<16],d2[1<<16];

main(){
	char*rp=mmap(0l,1l<<28,1,2,0,0ll);
	rd(n);
	int n1=n>>1;
	int n2=n-n1;
	long off=0;

	int k1=1;
	rep(i,n1){
		rd_long(a);
		rd_long(b);
		off+=b;
		a+=b;
		rep(j,k1){
			d1[j+k1]=d1[j]+a;
		}
		k1<<=1;
	}
	radix_sort(d1,k1);

	int k2=1;
	rep(i,n2){
		rd_long(a);
		rd_long(b);
		off+=b;
		a+=b;
		rep(j,k2){
			d2[j+k2]=d2[j]+a;
		}
		k2<<=1;
	}
	radix_sort(d2,k2);

	long r=1l<<62;
	int j1=0;
	int j2=k2-1;
	while(j1<k1&&j2>=0){
		long d=d1[j1]+d2[j2]-off;
		long a=d>=0?(--j2,d):(++j1,-d);
		chmin(r,a);
	}

	char wbuf[32],*wp=wbuf;
	wt(r);
	write(1,wbuf,wp-wbuf);
	_exit(0);
}