#include <stdio.h>
int max(int x,int y);
int main(void) {
int a,b,c,d,e,f,g;
scanf("%d %d %d %d",&a
,&b
,&c
,&d
); e=max(a,b);
f=max(c,d);
g=max(e,f);
return 0;
}
//max関数の定義
int max(int x, int y){
if(x<y){
return y;
}
else return x;
}
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