#include<stdio.h>
#include<algorithm>
main(){
    int x,y;
    int x2,y2;
    scanf("%d%d%d%d",&x,&y,&x2,&y2);
    int step = std::max(x,y);
    if(x==y && x2==y2){step++;}
    printf("%d\n",step);
}