Minimul elementelor de pe coloana unei matrici

#include <stdio.h>void main(void){

int i,j,n,a[20][20],s=0,min;printf("Introduceti numarul de linii:\n");scanf("%d",&n);printf("Introduceti numarul de coloane:\n");scanf("%d",&n);for(i=0;i<n;i++){

min=32000;for(j=0;j<n;j++){

printf("a[%d][%d]=\n",i,j);scanf("%d",&a[i][j]);

}}for(i=0;i<n;i++){

min=32000;for(j=0;j<n;j++){

if(min>a[j][i]) min=a[j][i];}

s=s+min;}printf("suma minimelor de pe fiecare coloana este:%d",s);scanf("%d",&n);

}