#include <stdio.h>
int main(void){
    int a, b, c, d;
    int yasai = 0;
    scanf( "%d %d %d %d", &a, &b, &c, &d );
    for( int i = 1; i * c <= b; i++ ){
        if( i + i * c > d ){
            break;
        }
        yasai = i;
    }
    printf( "%d\n", yasai );
}