// convolve one column of I by a 2rx1 max filter
void convMaxY( float *I, float *O, float *T, int h, int r ) {
int y, y0, y1, yi, m=2*r+1;
#define max1(a,b) a>b ? a : b;
#define maxk(y0,y1) { O[y]=I[y0]; \
for( yi=y0+1; yi<=y1; yi++ ) { if(I[yi]>O[y]) O[y]=I[yi]; }}
for( y=0; y<r; y++ ) { y1=y+r; if(y1>h-1) y1=h-1; maxk(0,y1); }
for( ; y<=h-m-r; y+=m ) {
T[m-1] = I[y+r];
for( yi=1; yi<m; yi++ ) T[m-1-yi] = max1( T[m-1-yi+1], I[y+r-yi] );
for( yi=1; yi<m; yi++ ) T[m-1+yi] = max1( T[m-1+yi-1], I[y+r+yi] );
for( yi=0; yi<m; yi++ ) O[y+yi] = max1( T[yi], T[yi+m-1] );
}
for( ; y<h-r; y++ ) { maxk(y-r,y+r); }
for( ; y<h; y++ ) { y0=y-r; if(y0<0) y0=0; maxk(y0,h-1); }
#undef maxk
#undef max1
}
int main() {
int i, N, A[102];
scanf("%d", &N);
for (i = 0; i < N; i++) {
scanf("%d", &A[i]);
}
printf("%d\n", maxk(A, N));
return 0;
}
