#include <stdio.h>
int max(int x,int y);
int main(void){
int a,b,c,d;
scanf("%d %d %d %d",&a
,&b
,&c
,&d
); printf("%d",max
(max
(a
,b
),max
(c
,d
))); return 0;
}
int max(int x,int y){
return (x>y)?x:y;
}
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