bzoj1800

#include <cstdio>

int sum[30],n;

int read_int () {
char c = getchar();
int re = 0;
for(;c > '9' || c < '0';c = getchar());
for(;c >= '0' && c <= '9';c = getchar())
re = re * 10 + c - '0';
return re;
}

int main () {

n = read_int();

for(int i = 1;i <= n;++i) {
sum[i] += read_int();
sum[i + 1] = sum[i];
}

int ans = 0;
for(int i = 1;i <= n - 3;++i) {
for(int j = i + 1;j <= n - 2;++j) {
for(int k = j + 1;k <= n - 1;++k) {
for(int l = k + 1;l <= n;++l) {
int t1 = sum[j - 1] - sum[i - 1];
int t2 = sum[l - 1] - sum[k - 1];
int t3 = sum[k - 1] - sum[j - 1];
int t4 = sum
- sum[l - 1] + sum[i - 1];
if(t1 == t2 && t3 == t4)
++ans;
}
}
}
}
printf("%d\n",ans);
}