#include <stdio.h>
double exp1(int n) {
double i,m = 1,ee = 1;
for(i = 1; i < n; ++i) {
m *= i;
ee += 1.0/m;
}
return ee;
}
double exp2(int n) {
double i = 1,m = 1,ee = 1;
while(i < n) {
m *= i;
ee += 1.0/m;
++i;
}
return ee;
}
double exp3(int n) {
double i = 1,m = 1,ee = 1;
do {
m *= i;
ee += 1.0/m;
++i;
}while(i < n);
return ee;
}
int main() {
int n;
printf("n = ");
scanf("%d",&n);
printf("for: %lf\n",exp1(n));
printf("while(): %lf\n",exp2(n));
printf("do_while(): %lf\n",exp3(n));
return 0;
}