#include <stdio.h>
void func(int n){
int i,j;
int count=0;
int sosuu;
for(i=2;i<=n;i++){
sosuu=1;
for(j=2;j<i;j++){
if(i%j==0){
sosuu=0;
break;
}
}
if(sosuu==1){
count++;
}
}
printf("%dは%d番目の素数\n", n
, count
); }
int prime(int n){
int i;
int sosuu = 1;
for(i=2; i<n; i++){
if(n%i == 0){
sosuu=0;
break;
}
}
return sosuu;
}
int main(void) {
int x;
for(int i=2; i<20;i++){
x = prime(i);
if (x == 1){
func(i);
}
}
return 0;
}
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