#include <stdio.h>
int main(){
    int x1,y1,x2,y2;
    scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
    printf("%d",(x1>x2?x1:x2)+(x1==y1 && x2==y2 && x2<x1));
    return 0;
}